Crankshaft position sensor replacement
The crankshaft-position sensor is one of the few sensors without whose signal the engine simply will not start.
Symptoms
- The car starts cold but stalls when warm and won't restart until it cools down.
What's included
- A typical failure pattern is that the vehicle starts cold but stalls when warm and will not restart until it cools down, because the sensor loses contact as it heats up. Sometimes the engine stalls while driving. We check the signal with an oscilloscope or scanner, assess winding resistance and inspect the trigger wheel and gap: a bent or dirty wheel causes the same symptoms even when the sensor is sound. After replacement, we verify cold and hot starts and confirm there are no misfires in live data.
Additional checks
- Sensor signal with an oscilloscope or scanner
- Sensor winding resistance
- No misfires in live data (after replacement)
Why it matters
A bent or dirty trigger wheel causes the same symptoms with a good sensor, so its condition and gap are always checked. After replacement, cold and hot starts are both verified.
More details
The crankshaft position sensor is one of the few sensors without whose signal the engine simply won't start. The classic failure pattern: the car starts fine when cold but stalls once warm and won't restart until it cools down — as it heats up, the sensor loses contact internally. Sometimes the engine stalls while driving. We check the signal with an oscilloscope or scanner, measure the winding resistance, and always inspect the condition of the reluctor ring and its gap: a bent or dirty ring produces the same symptoms with a perfectly good sensor. After replacement we check starting both cold and hot, and confirm there are no misfires in the live data.
Need a Technician Consultation?
Describe the vehicle and symptoms, and we will suggest which check to start with.
Book a Diagnostic