2012 V6 Mustang P0021 Fault: Diagnosis and Solutions After Motor Rebuild
I own a 2012 V6 Mustang with the engine recently rebuilt. After installing a new tune and conducting data logging, I noticed the check engine light is active, showing persistent fault codes P0018, P0-19, and P0021. I've verified that the timing on Bank 2 (driver's side) is correctly set and confirmed through physical inspection. I replaced both VCT solenoids and swapped the camshaft position sensors from Bank 1 to Bank 2 to test if the fault code would follow — no change in behavior. I also inspected the cam phaser components and found they move freely when the locking pin is removed, indicating no mechanical binding or sticking. The crankshaft sensor appears functional as Bank 1 timing data logs correctly. Additionally, the ECU reports accurate readings for Bank 1. Despite these checks, P0021 persists. I'm seeking expert advice on potential root causes — could this be a software issue, sensor misalignment, or an ECU calibration problem? Any insights would be greatly appreciated.
Sorry, I forgot to mention that the duty cycle differs significantly between banks: Bank 1 reaches a maximum of 0.80% during data logging, while Bank 2 shows a quick spike to about 0.15% before dropping back to zero. I also ran the vehicle with both VCT solenoids removed from Bank 2 — it reported -48/+48. When I reinstalled them while still outside the valve cover, the reading jumped back to -58/+58, which matches the value observed in data logging. This suggests the phasers are not stuck when fully disengaged, but the system is still failing to maintain proper timing under normal operation. Why does the timing shift only when solenoids are reconnected? Could this indicate a communication or calibration issue rather than mechanical failure?