P0337–P0387 Crankshaft Position Sensor A Circuit Low
The voltage on this circuit is sitting near zero. Typically a short to earth, or a sensor that has failed to its low end.
Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P0337 | Crankshaft Position Sensor A Circuit Low | Investigate soon |
P0387 | Crankshaft Position Sensor B Circuit Low | Investigate soon |
The definition
P0337: Crankshaft Position Sensor A Circuit Low.
P0337 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.
What to check first
Cheapest and fastest checks first:
- Unplug the sensor. If the reading jumps to full scale, the wiring is fine and the sensor has failed low.
- Check the sensor's 5V supply and its earth before condemning the sensor itself.
What actually causes this on a VAG
"Low" means the ECU sees the crankshaft sensor's signal line sitting at or near earth potential instead of pulsing as the crank turns. It is a complaint about the electrical circuit rather than about engine timing. The everyday experience is a no-start, or an engine that cuts out and refuses to fire until later.
Most likely causes, in order
- Oil or water in the connector bridging the pins. Common where the connector sits low on the engine near the oil filter housing. It costs nothing to check. Unplug it, inspect for oil and green corrosion, dry it out thoroughly and reseat it before deciding anything is faulty.
- Short to earth in the wiring. These sensors sit low down near the bellhousing and exhaust, so the loom rubs against brackets and heat shields. Look carefully along the whole run for rubbed-through insulation, and check where the loom crosses from body to engine.
- Sensor shorted internally. The sensor itself can pull the signal line down when it fails. Easy to separate from a wiring fault using the test in the note below, which also costs nothing.
Worth knowing: Unplug the sensor, clear the fault, switch on the ignition and crank briefly - it will not start with the sensor unplugged, and that is expected. If the stored code flips to the high or open-circuit version, the wiring up to the plug is not the thing shorting and the sensor was pulling the line down. If the low code comes back with nothing connected, the short is in the loom or connector and a new sensor will change nothing. Where the ECU only logs one general circuit fault rather than separate high and low versions, this test tells you nothing - measure at the connector instead.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.
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Common questions
What does P0337 mean?
P0337 means Crankshaft Position Sensor A Circuit Low. The voltage on this circuit is sitting near zero. Typically a short to earth, or a sensor that has failed to its low end.
Can I drive with P0337?
The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.