P0339
Crankshaft Position Sensor A Circuit Intermittent
The appearance of the standard OBD2 trouble fault code P0339 is an indicator that your vehicle ECU triggered a threshold alert for "Crankshaft Position Sensor A Circuit Intermittent". Understanding the root component breakdown helps avoid expensive diagnostic fees.
Driver's Summary
A P0339 fault code points directly to a problem with crankshaft position sensor a circuit intermittent that the ECM has confirmed over multiple drive cycles. Drivers typically experience engine dies randomly while driving, then restarts when this code is active. This is not a code to ignore — the underlying fault can rapidly worsen and lead to costly repairs if driving continues.
Symptoms
Engine dies randomly while driving, then restarts
Common Causes
- Loose electrical connection at sensor
- Frayed wiring shorting out
- Sensor failing when hot
- Excessive crankshaft end play
How to Fix
- 1 Clean and secure connector
- 2 Repair damaged wiring
- 3 Replace crankshaft position sensor
- 4 Measure crankshaft end play
Technical Explanation
Detection of P0339 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. Misfire rate is counted per cylinder over rolling windows and compared against two thresholds: a catalyst-damaging rate (triggers flashing MIL) and an emissions-exceeding rate (triggers solid MIL). The PCM logs which cylinder is misfiring based on crankshaft position at the time of each detected event. The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
Driving with an active P0339 fault risks accelerating damage to loose electrical connection at sensor and related components. The longer the fault persists, the more expensive the eventual repair becomes — what starts as a sensor or solenoid issue can escalate to major mechanical failure.
Mechanic's Pro Tip
The most common mistake with P0339 is replacing the sensor without verifying the reference voltage and ground integrity first. Use a scan tool to monitor the sensor's live output; a truly failed sensor shows a stuck, flatlined reading — a sensor that fluctuates but reads slightly off usually indicates a wiring or vacuum issue, not a dead sensor. Always spray electrical contact cleaner on the connector pins before condemning the sensor.
Sensor replacement: 150 - 350