2006 Audi S4 P0346 Code After Timing and Sensor Replacement
I have a 2006 Audi S4 (4.2L V8) and I’m getting code P0346. I tore into the engine because of the code and found Bank 2 timing was off, so I corrected the timing and, while I was in there, replaced the cam adjusters and the VVT solenoids. After reassembly, the car starts but it immediately sets the same P0346 code, as if nothing changed. I’ve checked continuity from the cam sensor to the ECU, and I’ve replaced the camshaft position sensor twice with no change. I’m looking for the most likely remaining causes and the best diagnostic steps to figure out why P0346 is still coming back after correcting Bank 2 timing and replacing those parts.
You nailed the right starting point by fixing Bank 2 timing and swapping cam adjusters and VVT solenoids. Since the P0346 (Camshaft Position Sensor Circuit Bank 2) code persists despite new sensors and wiring continuity checks, the most likely cause now is either the cam timing chain or tensioner slipping again or a mechanical timing issue not fully corrected. The ECU or wiring faults are less common but still possible if everything mechanical checks out.
Most likely culprits
- Cam timing chain or tensioner slipping: Even after correction, a worn chain or weak tensioner can let timing drift, causing the sensor signal to be off.
- Incorrect camshaft timing alignment: The timing may still be off by a tooth or the cam lobes not aligned perfectly, causing the sensor to see an unexpected signal.
- Wiring harness or connector issues: Intermittent wiring faults or poor grounds can mimic sensor failure despite continuity tests.
How to narrow it down
- Double-check cam timing marks with the engine at TDC on Bank 2 cylinder 1. Confirm cam lobes and crank pulley marks line up exactly per factory specs.
- Inspect timing chain tensioner and guides for wear or slack. A loose chain can cause timing to jump under compression.
- Use a scope or lab scope to monitor cam sensor waveform while cranking or running. Look for irregular or missing pulses that confirm sensor or mechanical timing issues.
- Wiggle wiring harness and connectors at the sensor and ECU while monitoring for signal dropouts or code resets.
- If all mechanical and wiring checks out, consider ECU input circuit faults or internal ECU failure, but this is rare.
Possible parts (if needed)
- Camshaft timing chain and tensioner (if slack or wear found)
- Camshaft position sensor Bank 2 (already replaced, but keep in mind)
- Wiring harness or connector repair kit for cam sensor circuit (if intermittent wiring faults found)
A few questions
- Did you verify the cam timing marks with the crankshaft at exact TDC on Bank 2 cylinder 1, or just eyeballed it?
- Is the timing chain tensioner hydraulic or mechanical on your 4.2L V8, and was it replaced or inspected during your repair?
- Have you checked the cam sensor signal waveform with a scope to confirm the sensor is producing a clean, consistent signal?
If you want to avoid chasing your tail, focus on confirming mechanical timing and chain tension first. The cam sensor and wiring are usually straightforward once continuity is confirmed.