P0321 Error: Faulty Crankshaft Sensor (VAG) (Solution)

Error code P0321 relates to the engine speed sensor (crankshaft sensor G28) and occurs in many VW/Audi/Seat/Skoda engines. The signal from the sensor is implausible or intermittently lost, which can lead to complete engine failure.


Typical error entry in the ECU:

Quote:

000801 - Sensor for engine speed (G28). P0321 - 000 - Implausible signal - Intermittent. Environmental conditions: Error status: 00110000 Error priority: 1. Error frequency: 1. Lost counter: 255 Mileage: 187,233 km Time: 0. Date: 2000.00.00 Time: 07:57:18

What does P0321 mean?
The crankshaft position sensor (G28) detects the engine speed and crankshaft position via a toothed wheel on the crankshaft. Without this signal, the engine control unit (ECU) cannot synchronize ignition and fuel injection. If the ECU detects an implausible or intermittent signal, a P0321 code is set. Common causes include a faulty sensor or an incorrect distance between the sensor and the toothed wheel.


Typical symptoms:
- Engine check light is on.
- Starting problems (engine doesn't start or starts with difficulty).
- The engine stalls while driving.
- The tachometer fluctuates or drops to zero.
- Stuttering


Most common causes:
- Faulty engine speed sensor (G28) (most common cause).
- Incorrect distance between the sensor and the encoder disc.
- Feeding wheel is dirty, damaged, or loose.
- Wiring/connector is corroded or damaged.
- Intermittent connection at the plug.
- If the donor variant is powered with +5V, check the power supply.


Diagnosis with VCDS:
- Autoscan: P0321 im Motorsteuergerät (01 - Motor)
- Observe the speed reading in the measurement block during the start attempt (if it remains at 0, there is no signal).
- Geber und Geberrad auf Verschmutzung/Beschädigung prüfen
- Measure the sensor's resistance and compare it to the target value.
- Check the connectors and wiring for loose connections.