P0346 on Mercedes-Benz: How to Diagnose & Fix
Camshaft Position Sensor A Circuit Range/Performance (Bank 2)
1 Mercedes-Benz model · 1 documented issue · 1 critical · $250-$4,000 repair
P0346 on Mercedes-Benz by model: symptoms, diagnosis and fix
On the M272 and M276 V6 engines (and the related M273 and M278 V8s) the camshaft position sensors and camshaft adjuster (VVT) solenoids sit in the timing cover, which is notorious for seeping oil. Oil gets past the sensor O-ring and into the electrical connector, then wicks up the wire strands inside the harness insulation by capillary action - owners on MBWorld and BenzWorld report finding oil dripping out of the connector and eventually inside the ME/ECU itself. Early symptoms are camshaft position codes such as P0016/P0017/P0346, rough running, misfires and lack of power. If the oil reaches the engine control module the repair escalates dramatically because the ECU and the full engine harness both need replacing and coding.
Common Symptoms
- Oil visible in or dripping from the camshaft sensor connector
- Rough idle, misfires, lack of power
- Check engine light with camshaft position/correlation codes
- Intermittent stalling or no-start
- Oil residue around the timing cover and cam magnets
How to Fix
At the first sign of oil at a cam sensor or adjuster solenoid connector, replace the sensor/solenoid with new O-rings and clean the connector cavity with electrical contact cleaner. Install sacrificial adapter 'pigtail' harnesses between each camshaft adjuster solenoid and the main harness so any future oil migration ruins a cheap pigtail instead of the main harness. Address the underlying timing-cover / cam-cover seepage. If oil has already reached the harness trunk or ECU, the harness section and ECU must be replaced - this is why the repair becomes far more expensive when it is ignored.
Sources for this issue (3)
P0346 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0346 mean on a Mercedes-Benz?
P0346 stands for "Camshaft Position Sensor A Circuit Range/Performance (Bank 2)." The camshaft position (CMP) sensor 'A' signal on bank 2 is present but out of range or not correlating with the crankshaft (range/performance). Often from timing-chain stretch on bank 2, a damaged reluctor, or air-gap/wiring noise. On Mercedes-Benz it is documented across 1 model: E-Class.
What are the most common causes of P0346?
The most common causes of P0346 are: Stretched/worn timing chain on bank 2, Damaged cam reluctor/timing wheel, Degrading bank 2 CMP sensor, Air-gap or loose sensor, Intermittent wiring/electrical interference. The specific cause varies by vehicle.
How much does it cost to fix P0346 on a Mercedes-Benz?
Published repair estimates on Mercedes-Benz range from $250 to $4,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.