Vehicle Speed Sensor A
The engine ECU needs to know how fast the car is going. Depending on the model, it gets that from a gearbox sensor or, as on many modern cars, from the ABS or ESP.
What the car has detected
The speed signal is missing or wrong. On many cars it comes from the ABS or ESP, so there may be a fault there too.
The car usually runs, but the speedometer, cruise control or automatic gear changes may fail. Have it checked soon, especially if the ABS or ESP light also comes on.
Symptoms
- Engine warning light on
- The speedometer reads nothing or reads wrong
- Cruise control does not work
- ABS or ESP warning lights on
Possible causes
- An ABS or ESP fault, or a faulty wheel sensor
- Damaged or corroded signal wiring or connectors
- Communication fault between control units
Checks for the garage
- Read the ABS and ESP codes and deal with those first
- Check connectors and wiring for corrosion or loose pins
- Move the wiring while watching the signal on the diagnostic tool to find intermittent breaks
Next step
Ask them to also read the ABS and ESP codes and to check the speed signal wiring and connectors.
Go to a garage soon. If the ABS or ESP also fails, drive more carefully, especially in the rain.