P1186 HYUNDAI – Fuel Pressure Monitoring – Minimum Pressure at Too Low Engine Speed

What does the P1186 code mean on a Hyundai?

The P1186 code is associated with a fuel rail pressure problem in a common rail diesel engine. The ECM (Engine Control Module) detects abnormal pressure in the fuel rail and may disable the injectors to prevent engine damage.

Possible Causes of the P1186 Code

  1. Faulty fuel pressure regulator valve (stuck open, preventing optimal pressure).
  2. Defective rail pressure sensor (incorrect fuel pressure measurement).
  3. Damaged rail pressure sensor wiring harness (short circuit, cut wire, poor connection).
  4. Poor electrical connection in the rail pressure sensor circuit.
  5. Mechanical failure of the high-pressure pump (internal issue affecting fuel delivery).
  6. Low-pressure fuel supply problem (failing lift pump, clogged fuel filter).

Possible Symptoms

  • Check engine light on (or service engine soon light)
  • Loss of engine power
  • Engine stalling or refusing to start
  • Irregular acceleration or jerking while driving
  • Excessive fuel consumption

How to Fix the P1186 Code?

  1. Check technical service bulletins (TSBs) to see if Hyundai has released a specific solution.
  2. Inspect the wiring harness and connectors of the rail pressure sensor (look for damaged wires, corroded or loose pins).
  3. Test the fuel pressure regulator valve to ensure it is functioning correctly and not stuck.
  4. Check the rail pressure sensor with a multimeter or OBD2 diagnostic tool.
  5. Inspect the high-pressure pump and fuel supply system (clogged fuel filter, fuel line leaks).
  6. Reset the code and test the vehicle after repair to see if the error reappears.

Conclusion

The P1186 code on a Hyundai indicates a fuel rail pressure imbalance, often caused by a sensor, regulator valve, or high-pressure pump issue. An accurate diagnosis with an OBD2 scanner is recommended to identify the exact source of the problem.

P1186 KIA – Fuel Pressure Too Low

Explanation of KIA Code P1186: “Fuel Pressure Too Low”

Severity

  • Level : 🔴 High (risk of engine stalling, damage to injectors or catalytic converter).
  • Urgency :
  • Engine may stall while driving (danger in traffic).
  • Risk of catalytic converter overheating (high replacement cost).

Common Symptoms

  • 🚨 Check engine light on (MIL) with code P1186.
  • 🐌 Loss of power during acceleration.
  • 💥 Hard starting (engine cranks for a long time before starting).
  • ⛽ Abnormally high fuel consumption.

Main Causes

  1. Fuel system problems :
  • Weak fuel pump (wear, clogged filter).
  • Faulty pressure regulator (in the rail or pump).
  1. Faulty fuel pressure sensor :
  • Incorrect data sent to the PCM.
  1. Fuel leaks :
  • Cracked pipes, leaking injectors.
  1. Electrical problems :
  • Cut/oxidized wires between the sensor and PCM.

Diagnostic Procedure (Detailed Steps)

Step 1: Fuel Pressure Test

  • Tools : Fuel pressure gauge (e.g., Actron CP7838).
  • Procedure :
  1. Connect the gauge to the Schrader valve on the injection rail.
  2. Turn the ignition on (without starting) → Pressure should reach 3-4 bar (gasoline) or 300-400 bar (diesel).
  3. Start the engine → Pressure should remain stable.

Step 2: Pressure Sensor Inspection (Rail)

  • Location : On the injection rail (common models: Kia Sportage, Sorento).
  • Electrical test :
  • Disconnect the connector and measure:
    • Power supply : 5V between the power terminal (red wire) and ground.
    • Signal : 0.5-4.5V variable with pressure.

Step 3: Fuel Pump Check

  • Listen for humming : When ignition is on, the pump should emit a buzz (2-3 seconds).
  • Pressure test : If < 3 bar, replace the pump or fuel filter.

Step 4: Leak Detection

  • Method : Visually inspect pipes and injectors. Use a UV leak detector (e.g., Tracerline) to locate micro-cracks.

Solutions & Costs

Problem Solution Average Cost
Weak fuel pump Replacement €200 – €600
Faulty pressure sensor Replacement €80 – €150
Clogged fuel filter Replacement €20 – €60
Fuel leaks Repair of pipes/injectors €50 – €300

Mistakes to Avoid

  • ❌ Neglecting the fuel filter : A clogged filter reduces pressure.
  • ❌ Forgetting to depressurize the system : Risk of fuel spray (use the Schrader valve).

Commonly Affected KIA Models

  • Kia Sportage (2011-2018) : Recurring fuel pump issues.
  • Kia Sorento (2.2L CRDi) : Failing pressure sensor.
  • Kia Ceed (1.6L GDI) : Injector leaks.

Practical Case

  • Problem : Code P1186 on a 2015 Kia Sportage with hard starting.
  • Diagnosis : Clogged fuel filter (pressure at 2.5 bar instead of 3.8 bar).
  • Solution : Filter replacement (€45) + injector cleaning.

Pro Tips

  1. Use a cleaning additive : Liqui Moly Jectron to maintain injectors.
  2. Check the pump relay : Swap it with an identical relay (e.g., headlights) for testing.

If the code persists after repair, consult a KIA garage equipped with advanced diagnostic tools (e.g., KDS) for an in-depth analysis! 🔧🚗⛽

P1186 MINI – O2 Sensor Heater Control Circuit, Bank 1 Sensor 2

P1186 MINI Possible Causes

  • Faulty O2 sensor
  • O2 sensor harness is open or shorted
  • Poor electrical connection in the O2 sensor circuit

How to Fix P1186 MINI Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine service soon warning light)

P1186 MINI Meaning

O2 Sensor Heater Control Circuit, Bank 1 Sensor 2 is the generic description for the P1186 Mini code, but the manufacturer may have a different description for your vehicle model and year. Currently, we do not have more information about the P1186 Mini OBDII code.

P1186 VOLKSWAGEN – Common Ground Short Circuit of Linear Oxygen Sensor to Positive

P1186 VOLKSWAGEN Possible Causes

  • Faulty O2 sensor
  • O2 sensor harness is open or shorted
  • Poor electrical connection in O2 sensor circuit

How to Fix Code P1186 VOLKSWAGEN?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1186 VOLKSWAGEN Meaning

Linear oxygen sensor common ground shorted to positive is the generic description for Volkswagen code P1186, but the manufacturer may have a different description for your vehicle model and year. Currently, we don’t have more information about Volkswagen OBDII code P1186.

P1187 – Fuel Pressure Monitoring – Regulator Valve Stick

P1187 Possible Causes

  • Faulty Fuel Pressure Regulator (FPR)
  • Faulty Rail Pressure Sensor (RPS)
  • Engine Control Module (ECM)

How to Fix Code P1187?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine warning light soon on)

P1187 Meaning

Fuel pressure monitoring is used to detect fuel problems and leaks in the high-pressure system.
The Engine Control Module (ECM) determines the rail pressure value based on engine operating conditions and controls the fuel pressure regulator to ensure the rail pressure reaches the required value.
The fuel pressure in the fuel line, including pumps and injector, is continuously monitored during engine operation.
If the rail pressure is too high, the fuel pressure regulator opens and some fuel is returned from the rail to the fuel tank via a return line. If the rail pressure is too low, the fuel pressure regulator closes.
The fuel pressure regulator closes. The fuel pressure regulator is installed at the rear end of the high-pressure accumulator.
In case of insufficient fuel supply in the fuel line, engine symptoms will occur such as stalling and inability to start.
If the fuel pressure monitoring in the engine’s fuel pressure line generates a threshold value, the ECM judges it as a fault and the P1187 code is set.

P1187 ACURA – Low voltage in the fuel tank temperature sensor circuit

P1187 ACURA Possible Causes

  • Faulty Fuel Tank Temperature (FTT) sensor
  • Fuel Tank Temperature (FTT) sensor harness is open or shorted
  • Fuel Tank Temperature (FTT) sensor circuit poor electrical connection
 

How to Fix P1187 ACURA Code?

Start by checking the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

 
 

Possible Symptoms

  • Engine Light On (or Service Engine Soon Warning Light)
 

P1187 ACURA Meaning

The Engine Control Module (ECM) monitors the fuel tank temperature sensor. The ECM sets the OBDII code when the fuel tank temperature sensor does not meet factory specifications.

P1187 AUDI – Open Circuit in Linear O2 Sensor Compensation Resistance

P1187 AUDI Possible Causes

  • Faulty O2 sensor
  • O2 sensor harness open or shorted
  • Poor electrical connection in O2 sensor circuit

How to Fix P1187 AUDI Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1187 AUDI Meaning

Linear O2 Sensor Compensation Resistance Open Circuit is the generic description for Audi P1187 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we don’t have more information about the P1187 Audi OBDII code.

P1187 BMW – O2 Sensor Heater Control Circuit, Bank 2 Sensor 2

P1187 BMW Possible Causes

  • Faulty O2 sensor
  • O2 sensor harness is open or shorted
  • Poor electrical connection in O2 sensor circuit
 

How to Fix BMW P1187 Code?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

 
 

Possible Symptoms

  • Engine light on (or service engine soon warning light)
 

P1187 BMW Meaning

O2 Sensor Heater Control Circuit, Bank 2 Sensor 2 is the generic description for Bmw P1187 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we don’t have more information about the P1187 Bmw OBDII code.

P1187 BUICK – Low Voltage in Engine Oil Temperature Sensor Circuit

P1187 BUICK Possible Causes

  • Faulty engine oil temperature sensor
  • Engine oil temperature sensor harness is open or shorted
  • Engine oil temperature sensor circuit poor electrical connection

How to Fix Code P1187 BUICK?

Start by checking the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine Light On (or Service Engine Soon Warning Light)

P1187 BUICK Meaning

The Powertrain Control Module (PCM) monitors the engine oil temperature sensor. The PCM sets the OBDII code when the engine oil temperature sensor is not within factory specifications.

P1187 CADILLAC – Low Voltage in Engine Oil Temperature Sensor Circuit

P1187 CADILLAC Possible Causes

  • Faulty engine oil temperature sensor
  • Engine oil temperature sensor harness is open or shorted
  • Poor electrical connection in the engine oil temperature sensor circuit

How to Fix Code P1187 CADILLAC?

Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

  • Engine light on (or engine service soon warning light)

P1187 CADILLAC Meaning

The Powertrain Control Module (PCM) monitors the engine oil temperature sensor. The PCM sets the OBDII code when the engine oil temperature sensor does not meet factory specifications.