Camshaft Position Sensor "A" Circuit Malfunction (Bank 1 or Single Sensor)
The P0340 code means the vehicle's onboard diagnostic system has detected: Camshaft Position Sensor "A" Circuit Malfunction (Bank 1 or Single Sensor). This is a critical severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- hard
- Estimated cost
- $20-$80 for cam sensor; $500-$1,500 if timing chain is involved
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Common Symptoms
- Engine cranks but will not start
- Intermittent stalling while driving
- Hard starting
- Check Engine Light on
Not sure this code matches what your car is doing? Try the guided checker: Cranks but won’t start →
Probable Causes (Ranked by Likelihood)
- Failed camshaft position sensor Very High
- Wiring fault to camshaft sensor (open, short, or damaged connector) High
- Timing chain skipped or stretched (sensor reads correctly but timing is off) Moderate
- Reluctor wheel damage on camshaft Low
Step-by-Step Diagnostic Procedure
-
Test the cam sensor with a multimeter. Most are Hall-effect sensors: check for 5V reference, ground, and signal wire continuity.
-
With a scan tool, monitor cam sensor signal. You should see a changing value as the engine cranks.
-
Inspect the sensor connector and wiring for corrosion or damage near the valve cover where heat is concentrated.
-
If the sensor tests good, check timing chain condition and cam reluctor wheel for damage.
Common Fixes by Vehicle
What techs usually find when diagnosing P0340 on specific vehicles — tap your vehicle for the fix and the exact part:
2002-2015 Nissan Altima/Maxima 3.5L VQ35DE easy DIY
Camshaft position sensor failure is extremely common on VQ35DE engines. Nissan TSB NTB04-061. The sensor is located on the back of the engine near the firewall (Bank 1). Replace with Hitachi CAM0016. While in there, inspect the wiring harness connector for oil contamination from valve cover leaks.
Labor: 30 min2007-2018 Jeep Wrangler/Grand Cherokee 3.6L easy DIY
The cam sensor on the Pentastar 3.6L fails around 80-100K. Located on the rear of the cylinder head. Mopar 5149025AA. If the engine has a no-start condition, also check the crankshaft position sensor since they can fail together. Worn timing chains cause erratic cam sensor signals -- check chain stretch.
Labor: 30 min2008-2019 Dodge Ram/Charger 5.7L Hemi easy DIY
Cam sensor located at the rear of the engine above the transmission bellhousing. Mopar 5149025AA. If you get P0340 intermittently, check the wiring harness where it routes along the back of the engine -- heat damage is common. A failing camshaft phaser can also cause erratic cam position signals on later Hemis with VVT.
Labor: 30 min2012-2019 Chevrolet Equinox/GMC Terrain 2.4L hard DIY
Timing chain stretch causes erratic cam sensor readings on the Ecotec 2.4L. If the engine has over 100K miles and rattles on cold start, the timing chain needs replacement -- not just the sensor. GM TSB #14-06-01-002A. Replace the chain, guides, and tensioner together. Check for engine oil level -- low oil accelerates chain wear.
Labor: 4-6 hoursFrequently Asked Questions
Can I drive with P0340?
Not reliably. A failing cam position sensor can cause the engine to stall without warning while driving. This is a safety concern and the vehicle should be repaired before regular driving.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0340 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
See All Codes & Fixes for Your Vehicle
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