1. Meaning of Buick Code P1392
The P1392 code indicates an inconsistency between the signals from the camshaft position sensor (CMP) and the crankshaft sensor (CKP).
- OBD-II Translation: “CKP/CMP Correlation Error – Intermittent Circuit”
- Consequences: Incorrect stalling, unstable idle, power loss, risk of engine damage (on interference engines).
2. Affected Buick Models
This fault frequently appears on:
- Buick Regal (1997-2004, 2011-2017)
- Buick LaCrosse (2005-2009, 2010-2016)
- Buick Century (1997-2005)
- Buick Enclave (2008-2017)
(Especially common on 3.1L V6, 3.8L V6, and 2.0T L4 engines)
3. Possible Causes (Ranked by Probability)
| Cause | Frequency | Associated Symptoms |
|---|---|---|
| 1. Faulty CMP Sensor | 40% | Hard starting, engine hiccup |
| 2. Timing Chain Problem | 30% | Metallic noise, power loss |
| 3. Defective Wiring/Connector | 20% | Intermittent code, flashing light |
| 4. Engine Oil Problem | 5% | Low oil pressure, faulty VVT |
| 5. ECU Failure | 5% | Multiple codes, electrical issues |
4. Step-by-Step Diagnosis
🔧 Step 1: Quick Check
- 1.1 Check the oil level and condition (dirty oil can block the VVT).
- 1.2 Visually inspect the CMP sensor connector (often located on the cylinder head).
📊 Step 2: Sensor Testing
- 2.1 Measure the CMP resistance:
- Normal values: 500-1500 Ω (depending on model).
- 2.2 Check the CKP signal with an oscilloscope (if possible).
🔌 Step 3: Wiring Inspection
- 3.1 Look for chafed/cut wires near the engine block.
- 3.2 Test continuity between sensors and ECU.
⚙️ Step 4: Mechanical Check (If necessary)
- 4.1 Check chain tension (sprocket markings).
- 4.2 Listen for abnormal noise from the chain tensioner.
5. Recommended Solutions
🛠️ For Buick 3.8L V6 (L36/L67)
- Common problem: CMP sensor submerged in oil.
- Solution: Replace the sensor (ACDelco #213-4439) + clean the connector.
🛠️ For Buick 2.0T (LHU)
- Known issue: Stretched timing chain.
- Solution: Chain kit + tensioner (approx. $600-1000).
🛠️ For Buick 3.1L V6 (LG8)
- Recurring problem: Oxidized CMP connector.
- Solution: Contact cleaning + dielectric spray.
6. Common Mistakes to Avoid
❌ Ignoring the code → Risk of engine damage (on interference engines).
❌ Using low-quality sensors → Prefer ACDelco or Delphi.
❌ Forgetting to check the oil → An oil change may solve the problem.
7. Average Repair Costs
| Repair | Cost (USD) |
|---|---|
| CMP Sensor Replacement | $80-200 |
| Complete Chain Kit | $600-1200 |
| Wiring Repair | $100-300 |
8. FAQ
Q: Can I drive with a P1392?
→ No, except to go to the garage. Risk of engine damage.
Q: The code returns after clearing, what to do?
→ Check the chain and sensors with an oscilloscope.
Q: Is it related to the timing belt?
→ No, except on very old models. Most recent Buicks have a chain.
9. Conclusion
The P1392 code on Buick requires:
- Electrical verification (sensors, wiring).
- Mechanical check (chain, tensioner).
- Professional diagnosis if the problem persists.
🔧 For an accurate diagnosis, specify:
- Exact model and year (e.g., Regal 2012 2.0T)
- Mileage
- Other symptoms (noises, power loss)
(Consult a certified GM mechanic for timing chain engines.)