P138D Code: Glow Plug Circuit/Performance Problem (Cylinder 4)

Common Symptoms

  • ❄️ Hard starting in cold weather (engine cranks for a long time before starting),
  • 🚗 Unstable idle or vibrations at startup,
  • ⚡ Misfires (especially when cold),
  • 💡 Engine fault light (Check Engine/ESP) illuminated,
  • 📉 White smoke from exhaust (unburned fuel).

Possible Causes

  1. 🔧 Faulty glow plug (cylinder 4): Internal failure (80% of cases).
  2. 🔌 Electrical issue in cylinder 4 circuit:
    • Cut/oxidized wires between GPCM and glow plug,
    • Defective or corroded connector.
  3. 💻 Control Module (GPCM) failure: Failure of the circuit dedicated to cylinder 4.
  4. ⚡ Faulty power supply:
    • Defective glow plug relay,
    • Blown fuse (check fuse box).

Step-by-Step Diagnosis

  1. 📏 Test glow plug #4:
    • Disconnect its connector,
    • Measure its resistance with a multimeter:
      • Normal value: 0.1 – 2 Ω (check manufacturer specification),
      • Infinite resistance = dead glow plug.
    • Alternative: Use a glow plug tester (red glow = OK).
  2. 🔍 Inspect wiring:
    • Follow the wire from GPCM to cylinder 4,
    • Look for burn marks, cuts, or corrosion.
  3. 🔋 Check power supply:
    • Test voltage at glow plug terminals during startup (should be ~10-12V for 2-10 sec).
  4. 🧩 Check GPCM and relay:
    • Scan the module for associated fault codes (e.g., P138A, P138B, P138C),
    • Test the relay (audible click + continuity).

Recommended Repairs

Faulty Component Action Average Cost
Glow plug #4 faulty Replace glow plug 20-80 €
Damaged wiring Repair wires/connectors 50-150 € (labor)
GPCM failure Replace module 150-400 € (part)
Relay/fuse faulty Replace part 10-40 €

⚠️ Important:

  • Never force start if a glow plug is faulty → risk of damaging the GPCM!
  • Replace glow plugs in sets (if >100,000 km) to avoid repeated failures.
  • Reset ECU after repair (using diagnostic tool).

Common Mistakes to Avoid

  • Neglecting connector sealing (causing oxidation),
  • Forgetting to calibrate GPCM after replacement (requires reprogramming).

ℹ️ Pro tip: If multiple P138x codes appear (e.g., P138C + P138D), the failure likely comes from the GPCM or relay, not the glow plugs!

If diagnosis exceeds your skills, consult a diesel mechanic 🔧. A specific diagnostic tool (e.g., Delphi, Snap-on) is often essential!

Sources: Manufacturer data (PSA, Renault, VAG), WSM, ETKA.

P138E Code: Glow Plug Circuit Problem – Cylinder 5

Key Symptoms

  • 🥶 Very difficult starting (especially below 10°C),
  • 🌫️ Thick white smoke from the exhaust (unburned fuel),
  • 📳 Idle vibrations or intermittent stalling,
  • ⚠️ Check Engine light on (+ possible glow plug light).

Probable Causes (by frequency)

  1. Faulty glow plug (cylinder 5):
    • Resistance out of specification (normal value: 0.1 – 2 Ω),
    • Internal short circuit or open circuit.
  2. Wiring problem (cylinder 5):
    • Cut, chafed, or oxidized wires (especially near the exhaust manifold),
    • Loose/corroded connector.
  3. GPCM Module Failure:
    • Failure of the circuit dedicated to cylinder 5,
    • Module overvoltage/overheating (often caused by a faulty glow plug).
  4. General power supply issue:
    • Stuck/faulty glow plug relay,
    • Blown fuse (check amperage ≥ 40A).

Step-by-Step Diagnosis

1. Test glow plug #5:

  • Disconnect the connector,
  • Measure the resistance between the + terminal and the glow plug ground: ∞ Ω (infinity) → Dead glow plug < 0.1 Ω → Short circuit > 2 Ω → Resistance too high
  • Alternative: Use a glow plug tester (should glow red in 5 sec max).

2. Inspect wiring (priority!):

  • Visually check the wire from GPCM to cylinder 5 (look for melted insulation, corrosion),
  • Test continuity wire by wire (multimeter in Ω mode),
  • Check the supply voltage: 10-12V during glow plug activation.

3. Check GPCM/Relay:

  • Scan the module: associated codes (P138A to P138D) indicate GPCM failure,
  • Test the relay:
    • Audible click upon activation,
    • Continuity between terminals 30-87 when powered.

Recommended Repairs

Failure Solution Estimated Cost
Glow plug #5 faulty Replace the glow plug 25-90 €
Damaged wiring Repair the harness 60-200 €
Defective GPCM Replace + reprogram* 200-500 €
Faulty relay/fuse Replace the part 10-50 €

* Some vehicles require GPCM pairing with the ECU (professional diagnostic tool required).

Common Mistakes to Avoid

  • Replacing the glow plug without checking the wiring → New fault code within 48h,
  • Forgetting to check the circuit ground (corrosion on chassis ground point),
  • Forcing the start with a faulty glow plug → Accelerated GPCM deterioration.

Technical Tips

  1. 🔧 Replace in sets: If >150,000 km, change all glow plugs (avoids cascade failures).
  2. ⚡ GPCM Protection: Always disconnect the battery before working on the circuit.
  3. 💡 Reset: Clear codes after repair + perform a glow plug cycle (without starting) for verification.

⚠️ Warning: On some engines (e.g., BMW M57, Mercedes OM642), accessing cylinder 5 often requires removing parts (particulate filter, piping).

ℹ️ If the code reappears after replacement: Have the GPCM timing/calibration checked (parameter setting via diagnostic tool) or check for a compression leak at cylinder 5 (weakens the glow plug effect).

Consult a diesel specialist if the diagnosis is complex! 🔧

P138F Code: General Glow Plug Circuit Problem

System: Global Control Circuit (GPCM) or Common Electrical Fault.
Clear Difference vs P138A-E:

  • ➡️ P138A to P138E = Problem on 1 specific cylinder.
  • ➡️ P138F = Collective anomaly (power supply, ground, module, or multiple glow plugs).

Common Symptoms

  • ❄️ Unable to start below 5°C (despite glow plug light),
  • 💡 Engine light + glow plug light on simultaneously,
  • 🌫️ Excessive white smoke from exhaust,
  • 🔌 Repeated relay clicking during startup,
  • ⚠️ Very unstable idle during first 2 minutes.

Priority Causes (check in this order!)

  1. ⚡ Faulty main power supply:
  • Blown main fuse (typically 40A to 80A),
  • Failed glow plug relay (stuck/burnt winding).
  1. 🔌 GPCM ground issue:
  • Corroded/loose ground cable (check chassis connection).
  1. 💻 GPCM Module Failure:
  • Internal short circuit, overheating, or software failure.
  1. 🔧 Multiple defective glow plugs:
  • Simultaneous wear (especially if >200,000 km),
  • Open or short circuit on multiple cylinders.
  1. 🧩 Damaged wiring harness:
  • Rubbed/burned main wires (e.g., contact with exhaust).

Step-by-Step Diagnosis

1. Quick Electrical Checks:

Component Test Expected Value
Main fuse Visual + continuity No break
Glow plug relay Power the coil Click + continuity 30-87
GPCM ground Measure resistance GPCM → Chassis < 0.5 Ω
GPCM power Voltage at power pin (ignition ON) Stable 12V

2. Glow Plug Test (collective):

  • Disconnect main GPCM connector,
  • Measure total resistance between power terminal and ground:
  Normal resistance = (Glow plug R) / number_of_cylinders  
  Ex: 6 plugs of 1Ω → ≈ 0.16 Ω
  • If ∞ Ω: Open circuit (fuse, cut wires),
  • If ≈ 0 Ω: General short circuit.

3. Advanced GPCM Scan:

  • Use a diagnostic tool capable of communicating with GPCM (e.g., Delphi, Snap-on),
  • Check live parameters:
  • Input voltage,
  • Current draw,
  • Concurrent fault codes P138A to P138E.

Recommended Repairs

Failure Solution Criticality
Blown fuse/relay Replace + check overcurrent cause 🔴 Urgent
Corroded ground Clean + tighten connection 🔴 Urgent
Faulty GPCM Replace + mandatory reprogramming* 🔴🔴 High
Multiple failed plugs Replace complete set 🟠 Medium
Damaged harness Repair defective section 🟢 Low

* GPCM often requires pairing with ECU (professional tool required).

Common Mistakes to Avoid

  • ❌ Changing GPCM without checking fuse/relay → New module burned out,
  • ❌ Forgetting GPCM reprogramming → Persistent fault code,
  • ❌ Replacing single glow plug on high-mileage vehicle → Recurring failure.

P138x Code Summary Table

Code Target Priority Test
P138A Cyl 1 Plug 1 resistance
P138B Cyl 2 Cyl 2 wiring
P138C Cyl 3 Plug 3
P138D Cyl 4 Cyl 4 power
P138E Cyl 5 GPCM ground
🛑 P138F System Fuse + Relay + GPCM Ground

Pro Tips

  1. 🔧 If P138F + other P138x codes: Fault always comes from GPCM or power supply.
  2. ⏱️ Check history: An old short circuit (e.g., melted plug) may have damaged relay/GPCM.
  3. 💡 Quick test: Temporarily short the relay (terminal 30 to 87):
  • If engine starts → Relay faulty,
  • If no change → Fuse/GPCM/wiring issue.

⚠️ Important: This code can immobilize vehicle in cold weather! Quick attention is crucial.

Definitive solution: Entrust diagnosis to specialist with manufacturer diagnostic tool (e.g., SD Connect for Ford/PSA, ODIS for VAG). Live PIDS data from GPCM is essential! 🔧

P1390 Code: Communication Problem Between the GPCM and the ECU

System: Communication network (CAN bus) or internal module failure.
Key difference vs P138x:

  • ➡️ P138x = Electrical/performance fault in a glow plug circuit.
  • ➡️ P1390 = Failure of digital communication between the engine control unit (ECU) and the glow plug control module (GPCM).

Common Symptoms

  • 🚫 Failure to start at temperatures < 5°C (even with glow plug indicator active),
  • 💻 Check Engine light + error message (“Glow plug system fault”),
  • 🔌 Complete absence of glow plug function (no relay click when ignition is on),
  • ⚠️ Associated fault codes (U0100, U0423, etc.) related to the CAN network.

Priority Causes (check in this order)

  1. 📡 CAN bus communication problem:
    • CAN-H / CAN-L wires cut, crushed, or short-circuited,
    • Oxidized connectors (GPCM or ECU).
  2. 🔌 Defective GPCM power supply/ground:
    • GPCM dedicated fuse blown (typically 10-15A),
    • Corroded ground (check chassis ground point).
  3. 💻 Internal GPCM failure:
    • Module no longer responding to ECU requests,
    • Damaged electronic components (swollen capacitors, burnt circuits).
  4. 🖥️ ECU failure:
    • Software or hardware failure of the control unit (rare).

Step-by-Step Diagnosis

1. Basic Electrical Checks:

Element Test
GPCM Fuse Visual check + continuity
GPCM Power Supply Measure voltage at power pin (ignition ON): 12V
GPCM Ground Resistance between GPCM ground → Chassis: < 0.5 Ω

2. CAN Network Test (digital multimeter required):

Measurement Normal Value Anomaly
CAN-H Voltage 2.5 – 2.7V (ignition ON) < 1V = Short circuit
CAN-L Voltage 2.3 – 2.5V (ignition ON) > 4V = ECU problem
CAN Resistance 60 Ω (between CAN-H and CAN-L) 0 Ω = Short circuit / 120 Ω = Cut wire

3. Advanced Diagnostic Scan:

  • Use a diagnostic tool capable of reading the GPCM (e.g., Delphi, Autel MaxiCOM),
  • Check:
    • GPCM communication status (module “Not detected”),
    • U0100 codes (loss of communication with GPCM),
    • Live data (GPCM output current/voltage = 0).

Recommended Repairs

Failure Solution Criticality
Blown fuse/faulty ground Replace fuse / clean ground 🔴 Urgent
Damaged CAN wires Repair faulty section + shielding 🔴🔴 High
Faulty GPCM Replace + mandatory reprogramming* 🔴🔴 High
Oxidized connectors Clean contacts with compressed air + contact spray 🟠 Medium

* The new GPCM requires pairing with the ECU (professional tool essential).

Mistakes to Avoid

  • ❌ Changing the GPCM without checking the CAN network → Recurring failure,
  • ❌ Ignoring associated codes (e.g., U0100) → Incomplete diagnosis,
  • ❌ Forcing startup → Risk of damaging the catalyst/DPF.

Practical Case (real PSA HDI example)

  1. Symptom: Failure to start when cold + P1390 code.
  2. Diagnosis:
    • GPCM fuse OK,
    • CAN-H Voltage = 0V (short circuit to ground),
    • Trace: CAN wires crushed under ECU housing.
  3. Repair:
    • Repair wires + insulate with heat shrink tubing.

Pro Tips

  1. 🔧 Quick test: Disconnect the GPCM connector → If the code changes to P1391 (open circuit), the GPCM is likely faulty.
  2. ⚡ Check history: A voltage spike (e.g., from incorrect jump start) can burn out the GPCM.
  3. 💡 Temporary solution:
    • Short-circuit the glow plug relay (pins 30-87) to power all glow plugs → Allows emergency start (avoid long-term use).

⚠️ Important: This code often immobilizes the vehicle in cold weather. Prompt attention is crucial. If basic checks fail, consult a specialist equipped with a manufacturer tool (e.g., Diagbox for PSA, SD Connect for Ford).

Technical data: SAE J1939 standards, ISO 15765-2, Manufacturer WSMs.

Acura P1399 Code: Variable Valve Timing Control (VTC) Problem – Diagnosis and Solutions

The default code P1399 is a common issue on Acura vehicles (particularly Honda/Acura models from 2000-2010). It indicates a malfunction in the Variable Valve Timing Control (VTC) system. This system optimizes engine performance and efficiency by adjusting camshaft timing in real time.
Here is a comprehensive guide to understanding and resolving this issue.

❌ Common Symptoms

  1. Hard starting (especially when cold): metallic rattling noises upon startup.
  2. Unstable idle: engine vibrations or hiccups.
  3. Loss of power: weak acceleration, especially at low RPM.
  4. Check engine light on: with stored code P1399.
  5. Increased fuel consumption.

🔧 Possible Causes

  1. Faulty VTC solenoid (most common cause): clogging or electrical failure.
  2. Clogged oil filter or degraded engine oil: insufficient pressure to operate the VTC system.
  3. Loose timing chain: premature wear of the tensioner or chain.
  4. Faulty Camshaft Position Sensor (CMP).
  5. Wiring problem: short circuit or corroded connector.
  6. Low oil pressure: worn oil pump or leak.

🔍 Diagnostic Steps

  1. Check engine oil:
    • Level and quality (replace if black or old).
    • Use a quality 5W-30 or 0W-20 oil (e.g., Honda/Acura Genuine Oil).
  2. Inspect the VTC solenoid:
    • Disconnect the electrical connector and measure resistance (normal value: 14–30 Ω).
    • Clean the solenoid with brake cleaner to remove deposits.
  3. Inspect the oil filter: Replace if necessary (prefer an OEM filter).
  4. Test oil pressure: Using a pressure gauge (target: ≥ 35 psi at idle).
  5. Scan real-time data:
    • Check CMP sensor values and VTC timing angles via an advanced OBD2 tool (e.g., HDS).
  6. Examine the electrical circuit: Look for damaged wires or corrosion on the solenoid connector.

🛠️ Recommended Repairs

  1. Replace the VTC solenoid:
    • Recommended part: OEM Solenoid 15860-R70-A01 (approximately $80–150).
    • Location: On the engine block, near the crankshaft.
  2. Change oil and filter:
    • Synthetic 5W-30 oil + Honda/Acura filter (e.g., 15400-PLM-A02).
  3. Update timing chain alignment (if necessary):
    • Check chain tension and replace the chain tensioner if excessive play.
  4. Replace the CMP sensor (associated code P0340/P0341): Part 37870-PND-A01.
  5. Reset the ECU: Clear the code with an OBD2 scanner after repair.

⚠️ Warning: On certain models (e.g., Acura TL 2004–2008, MDX, RDX), hard cold starting accompanied by rattling may indicate a design flaw in the VTC system. An ECU software update is sometimes required (consult a dealership).

💡 Prevention Tips

  • Change oil every 8,000 km max: The VTC system depends on oil pressure.
  • Use OEM parts: Generic solenoids often cause recurring issues.
  • Professional diagnosis if in doubt: A Honda HDS scanner allows for in-depth testing (e.g., checking live VTC parameters).

📊 Quick Reference Sheet

Code P1399
Definition VTC System Problem
Affected Acura Models TL, MDX, RDX, TSX, CL (2000–2015)
Most Common Solution Replace VTC solenoid + oil change

Conclusion

The P1399 code on Acura points to a failure in the variable timing system, often resolved by cleaning or replacing the VTC solenoid and a thorough oil change. Ignoring this issue can lead to premature timing system wear or significant power loss. Prompt action preserves engine health and restores original performance.

For complex cases, consult a Honda/Acura specialist mechanic equipped with the HDS tool!

Buick Trouble Code P1390: Crankshaft/Camshaft Timing Synchronization Issue – Diagnosis and Solutions

The P1390 code on Buick vehicles indicates a critical misalignment between the crankshaft and the camshaft. This error prevents the ECU from properly synchronizing injection and ignition, risking engine damage. Here is the complete guide.

❌ Common Symptoms

  1. Engine that does not start (caused by a loss of synchronization).
  2. Jerking and stalling during acceleration.
  3. Check engine light on + sudden loss of power.
  4. Abnormal noise (knocking or grinding near the timing system).

🔧 Main Causes

  1. Worn or misaligned timing belt/chain (major cause on Buick Century/Regal).
  2. Faulty crankshaft position sensor (CKP) or camshaft position sensor (CMP).
  3. Damaged reluctor wheel (missing or rusty teeth).
  4. Wiring problem: Short circuit, connector corrosion.
  5. Engine control module (ECU) fault (rare).

🔍 Diagnostic Procedure

  1. Check the timing belt/chain:
    • Inspect the tensioner and alignment marks (common models: Buick Century 1997-2005, Regal).
    • Look for broken teeth or excessive play.
  2. Test the CKP/CMP sensors:
    • Measure resistance (CKP: 850–1350 Ω, CMP: 200–1000 Ω, depending on model).
    • Inspect cables and connectors (oil deposits, oxidation).
  3. Examine the reluctor wheel:
    • Check for missing teeth or magnetic debris (clean with a dry cloth).
  4. Scan live data:
    • Compare CKP/CMP signals using an OBD2 tool (e.g., Tech2). A misalignment > 5° confirms P1390.

🛠️ Recommended Repairs

Problem Solution Recommended Parts (Buick Ref.)
Worn timing belt Replace belt + tensioner pulleys Gates kit TCKWP328 (for 3.1L V6)
Faulty CKP sensor Install new sensor (check air gap: 0.5–1.5 mm) ACDelco 213-1151
Damaged reluctor wheel Replace magnetic plate Delphi FG1114
Faulty wiring Repair wires or replace harness Standard Connector PT778

⚠️ Warning: A desynchronized timing system can cause piston-valve collision. Stop the engine if abnormal noises occur!

📊 Technical Sheet

Code P1390
Definition CKP/CMP synchronization error
Sensitive Buick Models Century, Regal, LaCrosse (1996–2010)
Urgency High (risk of engine failure)

💡 Key Tips

  • Use a specialized timing tool (e.g., Kent-Moore J-42450 for Buick) after replacing the timing system.
  • Check battery voltage during the procedure (low voltage distorts signals).
  • Prefer ACDelco/Delphi parts for optimal compatibility.
  • Reset the ECU after repair (clear code + relearn parameters).

Conclusion

The P1390 code on Buick indicates a critical mechanical or electrical problem between the crankshaft and camshaft. Prompt action is essential to avoid costly engine damage. Start by inspecting the timing system and sensors (CKP/CMP), then check the electrical circuit. If the fault persists, consult a specialist equipped with a GM Tech2 scanner for an in-depth analysis.

Cadillac Fault Code P1390: Crankshaft/Camshaft Synchronization Problem – Expert Diagnosis

The P1390 code on Cadillac indicates a critical desynchronization between the crankshaft (CKP) and camshaft (CMP), risking severe engine damage. Common on Northstar V8 and LFX engines, this fault requires prompt intervention.

🚨 Immediate Symptoms

  1. Failure to start or sudden engine shutdown.
  2. Metallic rattling near the timing case (loose chain).
  3. Sudden power loss + red engine warning light.
  4. Misfires (associated codes P0300-P0308).

🔧 Specific Cadillac Causes

  1. Stretched timing chain (premature wear on Northstar V8 > 150,000 km).
  2. Failed chain tensioner (hydraulic system blocked or leaking).
  3. Dirty or faulty CKP/CMP sensors (exposure to oil leaks).
  4. Damaged tone wheel (missing teeth or demagnetized magnet).
  5. Engine oil issue: low level, incorrect viscosity, or weak pump.

🔍 Step-by-Step Diagnosis (High Priority)

  1. Check oil pressure:
    • Minimum required: 20 psi at idle (use Kent-Moore J-21867 gauge).
    • Target: 40–60 psi at 2,000 RPM.
  2. Inspect timing chain:
    • Access via side cover (on CTS, STS, Escalade models).
    • Check lateral play (max 5 mm) and alignment marks.
  3. Test sensors:
    • CKP: Resistance 900–1100 Ω (ACDelco 12638548).
    • CMP: Signal voltage 0.3–5V while rotating (oscilloscope tool).
  4. Advanced GM scan:
    • Compare CKP/CMP signals via Tech2 or GDS2 (offset > 3° = confirmed fault).

🛠️ Validated Repairs (With References)

Faulty Component Solution Recommended OEM Parts
Timing chain Replace full kit (chains + tensioners + guides) GM 12640485 (Northstar V8 Kit)
Hydraulic tensioner Replace + check oil circuit ACDelco 12633825
CKP/CMP sensor Clean or replace (air gap: 0.5–1.5 mm) Delphi FG1022 (CKP), FG1105 (CMP)
Tone wheel Replace crankshaft rotor GM 12586459

⚠️ Critical Warning:
On interference engine Cadillacs (e.g., Northstar), desynchronization can cause piston-valve collision. Stop the engine immediately if abnormal noises occur!

💡 Key Procedures

  • Use GM timing tools:
    • J-42386 (crankshaft lock) + J-42387 (camshaft locks) for Northstar.
  • Post-repair check:
    • Reset ECU with Tech2, then perform a timing relearn.
  • Engine oil: Exclusively 5W-30 Dexos1 (e.g., Mobil 1 ESP).

📊 Technical Sheet

Code P1390
Definition CKP/CMP correlation error
At-Risk Models CTS, STS, SRX, Escalade (2000–2015)
Urgency MAXIMUM (risk of engine destruction)

Conclusion

The P1390 code on Cadillac reveals a potentially catastrophic engine synchronization fault. Major causes include timing chain wear, faulty sensors, or insufficient oil pressure. Immediate action is crucial:

  1. Check oil pressure and timing system condition.
  2. Replace faulty components with GM/ACDelco parts.
  3. Perform precise timing with dedicated tools.
    Do not attempt this repair without expertise – consult a GM-certified technician equipped with a Tech2/GDS2 scanner to avoid major repair costs.

Chevrolet P1390 Code: Crankshaft/Camshaft Timing Synchronization Problem – Diagnosis and Solutions

The P1390 code on Chevrolet vehicles (Silverado, Tahoe, Malibu, Equinox, etc.) indicates a critical desynchronization between the crankshaft (CKP) and the camshaft (CMP), preventing the ECU from controlling ignition and injection. Without prompt intervention, this fault can lead to serious engine damage.

🚨 Immediate Symptoms

  1. Engine hard to start or sudden stalling.
  2. Severe misfires and loss of power during acceleration.
  3. Check engine light on (sometimes flashing) + associated codes (P0016, P0340).
  4. Metallic noises near the timing cover (chain/timing gear).

🔧 Specific Chevrolet Causes

  1. Stretched timing chain (common on GM V6/V8 engines > 120,000 km).
  2. Failed hydraulic chain tensioner (oil leak or mechanical blockage).
  3. Dirty/defective CKP or CMP sensors (exposed to oil leaks).
  4. Damaged reluctor wheel (missing teeth or demagnetized magnet).
  5. Insufficient oil pressure (worn pump, degraded oil, clogged filter).

🔍 Step-by-Step Diagnosis

  1. Check oil pressure:
    • Minimum 15 psi at idle, ideal 35–60 psi at 2,000 rpm (use ACDelco T-80 gauge).
  2. Inspect the timing chain:
    • Access via side cover (models Silverado, Tahoe, Malibu 2.4L).
    • Check lateral play (max 6 mm) and alignment marks.
  3. Test sensors:
    • CKP: Resistance 850–1350 Ω (typical value V6 3.6L).
    • CMP: AC 0.3–3V signal on oscilloscope.
  4. Advanced GM scan:
    • Use Tech2 or GDS2 to compare CKP/CMP signals (offset > 2° = confirmed fault).

🛠️ Recommended Repairs (With OEM References)

Faulty Component Solution ACDelco/GM Parts
Timing chain Replace complete kit (chain + tensioners + guides) GM 12640486 (V8 5.3L) / 12633846 (V6 3.6L)
Hydraulic tensioner Replace + check oil supply ACDelco 12633825
CKP sensor Replace (air gap: 1.0 ± 0.5 mm) ACDelco 213-1151 (Silverado)
CMP sensor Clean or replace Delphi FG1105 (Equinox)
Reluctor wheel Inspect crankshaft rotor (bent/missing teeth) GM 12586459

⚠️ Critical Warning:
On Chevrolet interference engines (Ecotec, V8 Vortec), desynchronization causes piston-valve collision. Stop the engine at the first abnormal noises!

💡 Key Post-Repair Procedures

  1. Timing alignment:
    • Use GM tools J-42386 (crankshaft lock) and J-45027 (camshaft locks).
  2. ECU reset:
    • Clear code with Tech2/GDS2 + perform a timing relearn.
  3. Oil control:
    • Use a 5W-30 Dexos1 (e.g., Mobil 1 ESP) + GM filter PF64.

📊 Technical Sheet

Parameter Value
OBD2 Code P1390
Definition CKP/CMP correlation error
At-Risk Models Silverado, Tahoe, Equinox, Malibu (2004–2018)
Urgency MAXIMUM (risk of engine failure)

Comparison of Common Causes by Model

Model Recurring Problem Typical Solution
Silverado 5.3L Failed hydraulic chain tensioner Replace GM chain kit 12640486
Equinox 2.4L Oxidized reluctor wheel Change crankshaft rotor GM 12586459
Malibu 3.6L CMP sensor flooded with oil Replace + seal Delphi FG1105

Conclusion

The P1390 code on Chevrolet indicates a potentially destructive engine synchronization fault. Major causes include:

  1. Timing chain wear (especially on high-mileage V6/V8 engines),
  2. CKP/CMP sensor failure (aggravated by oil leaks),
  3. Insufficient oil pressure.

Recommended procedure:

  • Start by checking oil pressure and timing condition.
  • Replace faulty components with ACDelco/GM parts.
  • Perform precise timing alignment with dedicated tools and reset the ECU.
    Do not drive with this code – have the vehicle towed to a GM-certified technician equipped with a Tech2/GDS2 scanner to avoid costly repairs (e.g., engine replacement).

Dodge P1390 Code: CKP/CMP Synchronization Error – Diagnosis and Solutions

The P1390 code on Dodge vehicles (Ram, Charger, Challenger, Durango, etc.) indicates a critical misalignment between the crankshaft (CKP) and camshaft (CMP), compromising ignition and injection control. Without intervention, this fault can cause irreversible engine damage.

🚨 Immediate Symptoms

  1. Engine fails to start or suddenly stalls.
  2. Severe misfires and power loss under load.
  3. Flashing “Check Engine” light + related codes (P0016, P0340).
  4. Grinding/Clicking noises near the timing cover (loose chain).

🔧 Dodge-Specific Causes

  1. Stretched timing chain (common on Hemi V8 > 100,000 km).
  2. Hydraulic tensioner failure (internal leak or blockage).
  3. Faulty CKP/CMP magnet (cracked or demagnetized).
  4. Damaged reluctor wheel (missing teeth or corrosion).
  5. Low oil pressure (worn pump, clogged filter, old oil).

🔍 Step-by-Step Diagnosis

  1. Check oil pressure:
    • Minimum required: 10 psi at idle, 35+ psi at 2,000 RPM (Use Mopar 4902081AA gauge).
  2. Inspect timing chain:
    • Access via side cover (models: Ram 1500 5.7L Hemi, Charger R/T).
    • Check for stretch (misaligned marks > 6°) and guide condition.
  3. Test sensors:
    • CKP: Resistance 800–1300 Ω (typical Hemi 5.7L value).
    • CMP: AC 0.5–5V signal on oscilloscope.
  4. Advanced Mopar scanning:
    • Use WiTECH or DRB III to analyze CKP/CMP misalignment (> 3° = fault).

🛠️ Recommended Repairs (With Mopar References)

Faulty Component Solution Recommended Dodge Parts
Timing chain Replace full kit (chain + tensioners + guides) Mopar 68164189AA (Hemi 5.7L)
CKP Magnet Replace (air gap: 0.5–1.5 mm) Mopar 56027866AB (Ram 1500)
CMP Magnet Clean or replace Mopar 4894022AB (Charger 3.6L)
Reluctor wheel Inspect crankshaft rotor (replace if scratched/missing teeth) Mopar 4668272AB

⚠️ Critical Warning:
Hemi and Pentastar engines are interference engines! Desynchronization causes piston-valve collision. Stop the engine immediately if abnormal noises occur!

💡 Key Post-Repair Procedures

  1. Timing alignment:
    • Specific Mopar tools: Crankshaft lock 10238 + Camshaft lock 10243.
  2. ECU reset:
    • Clear codes via WiTECH + perform sensor relearn.
  3. Oil control:
    • Use 5W-20/5W-40 Full Synthetic (MS-6395 standard) + Mopar filter 5281090AB.

📊 Technical Sheet

Parameter Value
OBD2 Code P1390
Definition “Crankshaft/Camshaft Correlation Error”
Sensitive Models Ram 1500, Durango, Charger, Challenger (2005–2020)
Urgency MAXIMUM (engine failure risk)

Comparison of Recurring Issues by Model

Model Common Failure Solution
Ram 1500 5.7L Hemi Leaking hydraulic tensioner Mopar chain kit 68164189AA
Charger 3.6L V6 CMP magnet flooded with oil Replace Mopar 4894022AB
Durango 4.7L V8 Oxidized reluctor wheel (moisture) Change rotor Mopar 4668272AB

Conclusion

The P1390 code on Dodge indicates a highly critical timing fault. The primary causes are:

  1. Timing chain wear (especially on Hemi V8),
  2. CKP/CMP magnet failure (sensitive to oil leaks),
  3. Insufficient oil pressure.

Recommended Actions:

  1. Urgently check oil pressure and chain play.
  2. Replace faulty components with Mopar parts to ensure compatibility.
  3. Perform precise timing alignment with dedicated tools and reset the ECU via WiTECH.
    Do not start the engine again – have the vehicle towed to a certified Mopar technician. Ignoring this code can lead to engine destruction (cost: $5,000+).

Ford P1390 Code: Crankshaft/Camshaft (VCT) Synchronization Problem – Diagnosis and Solutions

The P1390 code on Ford vehicles (F-150, Escape, Focus, Mustang, etc.) indicates a critical desynchronization between the crankshaft (CKP) and the camshaft (CMP). This fault disrupts the VCT (Variable Camshaft Timing) system, risking severe damage to EcoBoost, Ti-VCT, or Duratec engines.

🚨 Immediate Symptoms

  1. Hard cold starting (metallic rattling).
  2. Sudden loss of power + violent jerking during acceleration.
  3. Flashing check engine light (associated codes: P0016, P0340).
  4. Excessive oil consumption or leaks (related to the VCT system).

🔧 Specific Ford Causes

  1. VCT solenoid failure (clogging, mechanical blockage).
  2. Worn VCT phaser (internal wear on EcoBoost 2.0L/3.5L > 120,000 km).
  3. Stretched timing chain (F-150 5.0L, Mustang GT models).
  4. Faulty CMP/CKP sensor (exposure to oil leaks/scale).
  5. Low oil pressure (failed pump, clogged filter, degraded oil).

🔍 Step-by-Step Diagnosis

  1. Check oil pressure:
    • Minimum required: 12 psi at idle, 35+ psi at 2,000 RPM (Ford 014-0072 Gauge).
  2. Inspect VCT solenoids:
    • Disconnect and measure resistance (5–15 Ω on EcoBoost).
    • Check anti-drainback filters (often clogged).
  3. Test sensors:
    • CKP: AC 0.5–4.5V signal (oscilloscope).
    • CMP: 200–1,000 Ω resistance (Focus 2.0L).
  4. Advanced Ford scan:
    • Use IDS/FDRS to analyze live VCT angles (offset > 4° = fault).

🛠️ Recommended Repairs (With Motorcraft References)

Faulty Component Solution Recommended Ford Parts
VCT Solenoid Replace (clean oil passages) Motorcraft CM-5193 (EcoBoost 2.0L)
VCT Phaser Change in pairs (left/right) Motorcraft CM-5191 (F-150 3.5L)
Timing Chain Replace full kit + tensioner Cloyes Kit 9-0667SB (Mustang 5.0L)
CMP Sensor Replace + seal Motorcraft DU-52 (Focus 1.6L)

⚠️ Critical Warning:
EcoBoost and Duratec Ti-VCT engines are interference engines! A desynchronization can cause piston-to-valve collision. Do not force starting!

💡 Key Post-Repair Procedures

  1. Timing alignment:
    • Specific tools: Crankshaft lock 303-507 + Camshaft lock 303-465 (for EcoBoost).
  2. VCT reset:
    • Perform a phaser relearn via IDS/FDRS (“VCT Learn” procedure).
  3. Oil maintenance:
    • Use 5W-30 Full Synthetic (WSS-M2C946-B1) + Motorcraft filter FL-910S.

📊 Technical Sheet

Parameter Value
OBD2 Code P1390
Definition “Crankshaft/Camshaft Position Sensor Correlation”
Sensitive Models F-150, Escape, Focus, Mustang (2008–2023)
Urgency MAXIMUM (risk of engine destruction)

Comparison of Common Failures by Model

Model Recurring Problem Solution
F-150 EcoBoost 3.5L Noisy VCT phasers when cold Motorcraft phaser kit CM-5191
Focus 1.6L Ecoboost Clogged VCT solenoid (obstructed filter) Replace CM-5193 + clean gallery
Mustang GT 5.0L Stretched chain (dry rattling) Cloyes chain kit 9-0667SB

Exclusive Ford Technical Tips

  1. Avoid generic parts:
    • Non-OEM solenoids cause relapses (recurrent P1390 error).
  2. Software update:
    • On Escape 2013–2016, an ECU recalibration (TSB 16-0114) often resolves the code.
  3. Check coolant:
    • An oil/coolant mix (failed head gasket) clogs VCT phasers.

Conclusion

The P1390 code on Ford points to a critical fault in the VCT system or engine timing. Priority actions:

  1. Urgently check oil pressure and the condition of VCT solenoids.
  2. Replace phasers or chain if necessary with Motorcraft parts.
  3. Perform a VCT relearn via IDS/FDRS.

Do not drive with this code! Have the vehicle towed to a certified Ford technician. Ignoring it can lead to:

  • Destruction of valves (cost: €3,000+),
  • Turbo damage (on EcoBoost).

📌 Note: For post-2018 models, a desynchronization can activate limp mode (power limited to 50%). Always use an IDS scanner for reliable diagnosis.