1. Diagnosis - Don't jump to replacing parts!
* Check for other codes: A related code (like P0017 for Bank 2) could help narrow down the problem area. Multiple codes often point towards a common underlying cause.
* Visual inspection: Start with the easy stuff. Look for any obvious signs of damage to wiring harnesses, connectors, or the sensors themselves (CKP and CMP). Check for broken wires, corrosion, or loose connections, particularly near the sensors.
* Verify oil level and quality: Low oil pressure or dirty/sludged oil can significantly affect camshaft and crankshaft sensor readings. Change the oil if it's old, dirty, or low.
* Check the valve timing system: In some cases (though less common on the PT Cruiser), issues with the valve timing system (e.g., a stretched timing chain or faulty tensioner) can cause this code. This is a more involved inspection and may require professional help.
* Use a scan tool with live data: A good OBD-II scan tool capable of live data viewing is crucial. Monitor the CKP and CMP sensor signals while cranking and running the engine. Look for erratic or out-of-range readings. This helps identify if a sensor is faulty or if there's an electrical problem.
2. Potential Causes and Solutions (in order of likelihood and cost):
* Variable Valve Timing (VVT) Solenoid: The VVT system adjusts camshaft timing. A faulty VVT solenoid can lead to timing discrepancies. Replacing this is relatively inexpensive and often solves the problem. There are usually two, one for each camshaft (bank 1 and bank 2).
* Camshaft Position Sensor (CMP): This is a common culprit. Replacing it is relatively straightforward.
* Crankshaft Position Sensor (CKP): Less likely than the CMP, but still a possibility. Replacing it is also relatively easy.
* Wiring harness issues: Look for shorts, opens, or broken wires in the harness leading to the CKP and CMP sensors. Repair or replace damaged wiring.
* Engine Oil Pressure: A lower than expected oil pressure can sometimes make the sensor readings erratic. Check the oil pressure itself.
* Timing Chain/Belt (Least likely, most expensive): A stretched or damaged timing chain (or, less commonly, belt) would be a serious mechanical issue. This requires significant expertise and labor to diagnose and repair.
3. Repair Steps (General):
* Replace a sensor: Accessing the CKP and CMP sensors on a PT Cruiser varies slightly depending on the year and engine. Consult a repair manual specific to your vehicle for detailed instructions. The process generally involves disconnecting the battery, removing the sensor(s), and installing the new one(s). Torque specifications are crucial to avoid damage.
* Repair wiring: If you find damaged wiring, carefully repair it using appropriate connectors and electrical tape. Always disconnect the battery before working on any electrical components.
Important Considerations:
* Repair Manual: A repair manual (Haynes or Chilton) specific to your year and model PT Cruiser is highly recommended. It will provide detailed diagrams, instructions, and torque specifications.
* Professional Mechanic: If you're not comfortable working on your vehicle, take it to a qualified mechanic. Improper diagnosis or repair can lead to further damage.
* Code Clearing: After making any repairs, clear the code using your scan tool and test drive the vehicle to see if the code returns.
The P0016 code isn't a simple fix-it-all situation. Systematic troubleshooting, starting with visual inspection and progressing to live data analysis, is crucial to accurately identify the root cause. Don't just start replacing parts; you'll waste time and money.
