P0346: How to Diagnose & Fix — Camshaft Position Sensor A Circuit Range/Performance (Bank 2)
2 vehicles · 2 makes · $250-$4,500 repair
How to diagnose and fix P0346: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Ford Expedition · 2004–2014
The 5.4L 3-valve (3V) Triton V8 in 2004-2014 Ford Expedition is notorious for cam phaser failures and timing chain stretch, representing one of the most common and expensive repairs on these trucks. The VCT (Variable Camshaft Timing) system uses oil pressure to actuate the cam phasers - when phasers wear out or chains stretch, the engine sets multiple camshaft correlation codes and rattles on startup. The factory oil pump also wears out at similar intervals, compounding the problem. Running low on oil or using the wrong viscosity dramatically accelerates failure. Left unrepaired, a failed phaser can cause a chain to jump timing, resulting in bent valves and catastrophic engine damage. Repair typically requires complete timing system replacement including both cam phasers, all four timing chains, guides, and tensioners - a 12-16 hour job.
Common Symptoms
- Loud rattling/knocking from engine on cold start (top-end rattle)
- Check engine light with codes P0340, P0341, P0344, P0345, P0346, P0349 (cam sensor/phaser codes)
- Codes P0016, P0017, P0018, P0019 (camshaft-crankshaft timing correlation)
- Rough idle, especially when cold
- Engine surging at idle
- Loss of power and poor fuel economy
- Rattle that worsens on acceleration at low RPM
- Multiple misfire codes accompanying timing codes
How to Fix
Complete timing system overhaul: replace both VCT cam phasers, timing chains (primary and secondary), all chain guides, and tensioners as a complete kit. Motorcraft timing chain and phaser kit (TKIT-2004A-MGA or dealer equivalent) is recommended. Also replace the oil pump if over 80,000 miles - worn pump cannot supply adequate oil pressure for VCT system. Use 5W-20 full synthetic oil only. Change oil every 5,000 miles maximum. Labor: 12-16 hours on Expedition due to 4WD and engine mounts.
Sources for this issue (1)
Mercedes-Benz E-Class · 2006–2016
On the M272 and M276 V6 engines 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 owners describe five-figure bills when it is ignored.
Sources for this issue (3)
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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?
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.
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?
Repair costs for P0346 range from $250 to $4,500, depending on the vehicle and root cause.
Which vehicles are affected by P0346?
Au7o has documented P0346 across 2 vehicle models from 2 manufacturers: Ford, Mercedes-Benz.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.