The P0016 Code, indicating a “Crankshaft Position – Camshaft Position Correlation Bank 1 Sensor ‘A'” error, is a common issue in vehicles like the Toyota Tacoma. This code signals a discrepancy between the crankshaft and camshaft positions, potentially leading to performance problems. This article outlines a troubleshooting process for diagnosing the root cause of a P0016 code in a 2005 Toyota Tacoma with 133,000 miles that experiences the code reappearing after idling and exhibits a warm start issue.
Potential Causes of P0016
The P0016 code can stem from various issues, including:
- Timing Chain Problems: A stretched or skipped timing chain tooth can disrupt the synchronization between the crankshaft and camshaft.
- Faulty Sensors: A malfunctioning camshaft or crankshaft position sensor can provide inaccurate readings, triggering the code.
- Oil System Issues: Dirty oil, clogged oil control valve (OCV) filters, or malfunctioning OCV valves can impede proper engine timing.
Troubleshooting Steps Undertaken
The following diagnostic steps were performed to pinpoint the cause of the P0016 code:
1. Camshaft Position Sensor Swap
Process: The camshaft position sensors for bank 1 and bank 2 were swapped to determine if the code would shift to a P0018 (the equivalent code for bank 2).
Result: The engine ran poorly and generated multiple error codes, but not a P0018. This doesn’t definitively rule out a faulty sensor as a new sensor wasn’t available for comparison. A question remains whether bank 1 and 2 cam sensors are interchangeable.
2. OCV Filter Inspection
Process: The OCV filter on bank 1 was removed and inspected for blockage.
Result: Minimal sludge was found, unlikely to significantly restrict oil flow. The bank 2 filter was inaccessible behind the alternator.
3. OCV Valve Testing
Process: Both OCV valves were removed, tested for functionality using 12 volts, and their resistance was measured.
Result: Both valves operated correctly with no sticking and exhibited a resistance of 7.3 ohms, within the acceptable range. Cleaning wasn’t deemed necessary.
4. Crank Sensor Inspection
Process: Access to the crank sensor was limited, preventing inspection.
5. Timing Chain Inspection
Process: The timing chain markings were compared to a reference guide (TOYO Headquarters). The crankshaft was aligned to its 0 mark, and the alignment of the camshaft sprockets was observed.
Result: Both bank 1 and bank 2 VVTi camshaft sprockets were advanced approximately 1/3 to 1/2 of a timing chain link relative to their marks when the crankshaft was at 0. There was uncertainty about the proper application of the guide, raising questions about the accuracy of the observation.
Crankshaft aligned to the 0 mark.
Bank 1 VVTi camshaft sprocket misalignment.
Bank 2 VVTi camshaft sprocket misalignment.
Timing chain tensioner fully extended, indicating potential chain stretch.
Conclusion
The timing chain appears stretched, potentially explaining the P0016 code. The observed misalignment of the camshaft sprockets, coupled with the fully extended tensioner, supports this conclusion. Further investigation is needed to confirm the diagnosis. A timing chain replacement is planned, along with engine cleaning procedures to address sludge buildup. This experience highlights the importance of thorough engine inspections when purchasing used vehicles.
