P0340

Camshaft Position Sensor A Circuit Bank 1 or Single Sensor

Ignition / cam-crank timing Generic OBD-II High

What it means

P0340 means the engine control module lost or couldn't make sense of the signal from the camshaft position sensor. That sensor tells the ECM where the camshaft is so it can time fuel injection and spark; without a reliable signal the engine can be hard to start, stall, or refuse to start at all.

High

Can I keep driving? Risky — a lost camshaft signal can cause hard starting, stalling, or a no-start, so drive as little as possible and be ready for it to quit.

Real-world scan data

Seen in

8,070

scans in the past year

Found in

1.3%

of scans

2.3%

of scans that found faults

Appears alongside · share of P0340 scans

P0335in 17.7% of scans

P0016in 14.3% of scans

P0201in 9.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Hard starting, long cranking, or intermittent no-start
Stalling or cutting out while driving
Misfire, hesitation, or reduced power

Common causes

Most likely first

Failed camshaft position sensor (the most common cause)Likely
Damaged wiring or a poor/corroded connector at the sensorCommon
Metal debris or oil contamination on the sensor tipCommon
Damaged reluctor/tone ring or timing chain issue affecting the signalLess often
Failed engine control module (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and check the camshaft sensor connector for oil, corrosion, or looseness.
Inspect the sensor wiring for chafing or breaks back to the ECM.
Test the sensor signal (and its power/ground) with the engine cranking; replace the sensor if it drops out.
If the signal is erratic, inspect the reluctor ring and verify timing components.
Clear the code and confirm the car starts and runs without the fault returning.

FAQ

Quick answers

Is it safe to drive with P0340?+

Not really. The engine may stall or fail to restart without warning, so treat it as urgent rather than driving on it.

Can I just clear P0340?+

Clearing it won't help — the fault returns as soon as the sensor signal drops again, and the car may leave you stranded until it's repaired.

Read & clear P0340 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX