P0339
Crankshaft Position Sensor A Circuit Intermittent
Ignition / crank position
Generic OBD-II
High
What it means
P0339 means the crankshaft position signal is cutting out intermittently. The ECM depends on it to time spark and fuel injection, so a signal that drops in and out typically shows up as random stalling, hard or no-starts, and rough running that come and go — often triggered by engine heat or vibration. It's worth fixing before it strands you.
High
Can I keep driving? Risky — an intermittent crank signal can cause sudden stalling or a no-start that leaves you stranded; fix promptly.
Common symptoms
What you'll notice
- Check-engine light on
- Intermittent stalling
- Hard starting or an occasional no-start
- Rough running or hesitation that comes and goes
- Tachometer dropping out momentarily
Common causes
Most likely first
- Failing crankshaft position sensor (often heat-sensitive)Likely
- Loose or corroded connector, or chafed/damaged wiringCommon
- Damaged reluctor/tone ring or metal debris on the sensor tipCommon
- Wiring routed near heat or moving parts, cutting the signal intermittentlyLess often
- Rarely, a failing ECMLess often
How to diagnose & fix
Work through it in order
- Wiggle- and heat-test the sensor and harness while watching the RPM signal in live data.
- Inspect the connector and wiring for chafing, corrosion, or a loose pin.
- Check the sensor air gap and the tone ring for damage or debris.
- Replace the crankshaft position sensor if the signal drops out.
- Clear the code and re-test, including a hot restart.
FAQ
Quick answers
Is it safe to drive with P0339?+
Not really — an intermittent crank signal can cut spark and fuel without warning, causing a stall or no-start in traffic. Have it fixed before relying on the car.
Can I just clear P0339?+
Clearing it won't help; because the fault is intermittent it returns the next time the signal glitches. The sensor or wiring has to be repaired.
Related codes
Often seen with P0339
Read & clear P0339 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX