# P0339: Crankshaft Position Sensor "A" Circuit Intermittent **Verdict:** Drive to a shop this week Engine sensors - Generic OBD-II code, applies to all gasoline cars and light trucks sold in the US since 1996. - **Typical cost:** $100-$450 - **Urgency:** This week - **Most likely:** Loose connector or chafed sensor wiring - **DIY?:** Steps 1-3 ## Quick answer P0339 means the crankshaft position signal is cutting in and out. The engine computer saw the signal drop out briefly, then return, which is often caused by a loose connector, chafed wiring, or a sensor that fails when hot. Because the engine needs this signal to run, momentary stalling or stumbling can happen. ## What does P0339 mean? The crankshaft position sensor tells the engine computer how fast the crankshaft is turning and where each piston is. It reads teeth on a reluctor ring attached to the crankshaft, balancer or flywheel. Without that signal the computer cannot time spark or fuel injection, so even a brief dropout can make the engine stumble, cut out or stall. P0339 is an intermittent code for crank sensor "A", the first or only crank sensor. The computer sets it when the signal disappears or becomes erratic for a short time and then recovers, while other inputs such as the cam sensor show the engine was still turning. Because the fault comes and goes, the car may run perfectly when you take it in. Many vehicles set this code on the first trip it happens. Freeze-frame data, which records conditions at the moment it set, is especially useful for finding the pattern. ## What are the symptoms of P0339? - Engine stumbles, cuts out briefly or stalls, then restarts - Tachometer needle drops to zero for a moment while driving - Occasional hard start or extended cranking - Problem appears over bumps, in rain, or once the engine is hot - Check engine light on, sometimes with no symptoms at the time ## What causes P0339? Ranked from most to least likely. Check them in this order: the cheap, common causes first. 1. **Loose or corroded sensor connector** (most common). A connector whose locking tab has broken, or whose pins are corroded or oil-soaked, can lose contact for a fraction of a second over bumps or as the engine rocks. Crank sensor connectors often sit low on the engine where splash and road salt reach them. Wiggling the connector while watching rpm on a scan tool often reproduces the dropout. 2. **Chafed or heat-damaged wiring** (common). The crank sensor harness runs close to the exhaust, the starter or moving parts. Insulation that has rubbed through can briefly short to ground, and a conductor broken inside its insulation may connect only part of the time. These faults often get worse in wet weather or once engine heat makes parts expand. 3. **Sensor failing when hot** (common). A crank sensor with internal damage may work cold, then drop out once it heats up, and recover after cooling. That pattern can set P0339 before the sensor fails completely and sets P0335. It can happen at any mileage. A shop watches the signal on a scope while heating the sensor or after a long drive. 4. **Charging system or ground problem** (less common). A weak engine ground, a loose battery cable or a failing alternator producing electrical noise can corrupt the small crank signal or the sensor's power supply on Hall-effect designs. The dropouts may line up with heavy electrical loads such as the fans or rear defroster. Checking grounds and battery connections is cheap and should come early. ## How do you diagnose P0339? 1. Review freeze-frame data to see the engine speed, temperature and conditions when P0339 set. 2. Inspect the crank sensor connector for a broken lock, corrosion or oil, and the harness for rubbing or heat damage. 3. Wiggle-test the harness and connector while watching rpm on a scan tool or the signal on a scope. 4. Check battery cables, engine grounds and charging voltage, then test the sensor hot and cold. 5. Road-test over rough pavement and through a full warm-up to try to reproduce the dropout before replacing parts. ## How do you fix P0339, and what does it cost? | Fix | Typical cost | What it involves | | --- | --- | --- | | Repair connector or sensor wiring | $100-$350 | Replace a broken connector or repair chafed wire and re-route it. | | Replace crankshaft position sensor | $150-$400 | Most sensors are reached from under the car; some need other parts removed. | | Repair engine grounds or battery cables | $100-$300 | Clean or replace corroded ground straps and terminals. | Full price breakdowns: [crankshaft position sensor replacement cost](/cost/crankshaft-position-sensor-replacement). ## Is it safe to drive with P0339? > **Drive to a shop this week.** Drive only if you must until it is fixed. A crank signal dropout can stall the engine with no warning, and power steering and brake assist get much heavier when it does. ## Will P0339 fail an emissions test? With P0339 stored and the check engine light on, the car fails an OBD-based emissions test. Because this is an intermittent fault, the light may go off and the code may still be stored as history. After the repair, clear the code and drive several days until the readiness monitors are complete before testing. ## After the repair: clearing P0339 Clear the code and drive in the conditions that set it, such as rough roads, rain or a long drive to full temperature. Watch for any tachometer flicker or stumble. Since intermittent faults can take time to reappear, the repair is proven when P0339 has not returned as a pending code after a couple of weeks of normal driving. ## How to prevent P0339 - Make sure the crank sensor connector clicks fully into its lock after any nearby repair. - Keep the crank sensor harness clipped away from the exhaust, starter and moving parts. - Fix oil leaks near the sensor so oil does not wick into the connector. - Clean and tighten battery terminals and engine ground straps as part of regular maintenance. ## Codes often seen with P0339 - [P0335](/codes/p0335): Crankshaft Position Sensor "A" Circuit - [P0336](/codes/p0336): Crankshaft Position Sensor "A" Circuit Range/Performance - [P0340](/codes/p0340): Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor) - [P0300](/codes/p0300): Random/Multiple Cylinder Misfire Detected ## Frequently asked questions ### Can I drive with a P0339 code? Only carefully and briefly. An intermittent crank signal can stall the engine without warning, which makes steering and braking harder. If the car is running well, drive straight to a shop and avoid highways. If it has already stalled, consider having it towed instead. ### What does crankshaft sensor intermittent mean? It means the crank sensor signal briefly dropped out or became erratic and then came back. The computer noticed the gap while other signals showed the engine was still turning. Loose connectors, chafed wiring and a sensor failing when hot are the usual causes, so the problem often comes and goes. ### How much does it cost to fix P0339? Most P0339 repairs cost $100 to $450 at an independent shop. Connector or wiring repairs run about $100 to $350, a new crank sensor $150 to $400, and ground or battery cable repairs $100 to $300. Diagnosis time may add to the bill because intermittent faults take longer to find. ### Why does my car stall and then restart fine? A brief loss of the crank signal is a common reason. The engine dies when the signal drops, then restarts once the connection or sensor recovers. Heat-sensitive crank sensors and loose connectors are typical. If P0339 is stored, that strongly suggests the crank circuit is the cause. ### Can a bad battery cause P0339? It can contribute. A loose battery cable, corroded terminal or poor engine ground can disrupt the sensor's power or ground, especially on Hall-effect sensors. A weak battery also lowers voltage during cranking. Checking and cleaning connections is quick and inexpensive, so do it before replacing the sensor. ### Should I replace the crank sensor for P0339? Not before checking the connector and wiring, which cause intermittent codes very often. If the wiring is sound and the sensor fails a hot test on a scope, replacing it makes sense. A quality sensor is worth the small extra cost, since poor parts can cause repeat dropouts. ### Can P0339 turn into P0335? Yes, a sensor or wire that fails intermittently today may fail completely later. When the signal is lost for longer, the computer may store P0335 instead, and the engine may not start at all. Fixing P0339 early avoids being stranded by a sudden no-start. ### Can I fix P0339 myself? You can do the first checks yourself: inspect the connector lock, look for chafed wiring, and clean battery terminals and grounds. Replacing an easy-to-reach crank sensor is a moderate job. Proving the fault usually needs a scope or scan tool watching the signal while wiggling the wiring. ### Why does the tachometer drop to zero while driving? On most cars the tachometer reads the crank signal, so a sudden drop to zero usually means the crank signal was lost for a moment. That matches P0339. If the engine also stumbles or stalls at the same time, the crank sensor circuit should be checked soon. ### Will P0339 pass inspection? No, P0339 with the check engine light on fails an OBD-based emissions test in most states. Even if the light goes off, the code may remain stored, and clearing it resets readiness monitors. Fix the cause and drive normally until the monitors complete before testing. ## Sources - [SAE J2012: Diagnostic Trouble Code Definitions](https://www.sae.org/standards/content/j2012_201812/) - [EPA: On-Board Diagnostics (OBD)](https://www.epa.gov/state-and-local-transportation/vehicle-emissions-board-diagnostics-obd) ## Other engine sensors codes - [P0325 Knock Sensor 1 Circuit (Bank 1 or Single Sensor)](https://diagxcar.com/codes/p0325) - [P0326 Knock Sensor 1 Circuit Range/Performance (Bank 1 or Single Sensor)](https://diagxcar.com/codes/p0326) - [P0327 Knock Sensor 1 Circuit Low (Bank 1 or Single Sensor)](https://diagxcar.com/codes/p0327) - [P0332 Knock Sensor 2 Circuit Low (Bank 2)](https://diagxcar.com/codes/p0332) - [P0335 Crankshaft Position Sensor "A" Circuit](https://diagxcar.com/codes/p0335) - [P0336 Crankshaft Position Sensor "A" Circuit Range/Performance](https://diagxcar.com/codes/p0336) - [P0340 Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)](https://diagxcar.com/codes/p0340) - [P0341 Camshaft Position Sensor "A" Circuit Range/Performance (Bank 1 or Single Sensor)](https://diagxcar.com/codes/p0341) - [P0344 Camshaft Position Sensor "A" Circuit Intermittent (Bank 1 or Single Sensor)](https://diagxcar.com/codes/p0344) - [P0345 Camshaft Position Sensor "A" Circuit (Bank 2)](https://diagxcar.com/codes/p0345) ## Symptoms - [Why does my car stall while driving?](https://diagxcar.com/symptoms/car-stalls-while-driving) - [Why does my car crank but not start?](https://diagxcar.com/symptoms/car-cranks-but-wont-start) - [Why won't my car start?](https://diagxcar.com/symptoms/car-wont-start) ## Repair costs - [Crankshaft position sensor replacement cost](https://diagxcar.com/cost/crankshaft-position-sensor-replacement): $150-$500 --- Source page: https://diagxcar.com/codes/p0339 Updated: 2026-11-03 General information, not a substitute for a qualified mechanic.