Mercedes-Benz W140 ASR light comes on and the car goes into limp mode
W140 ASR light comes on and the car goes into limp mode, what is usually the cause?
The most common cause is the throttle or accelerator pedal position sensor not giving the control unit the correct data. The brake light switch, fuses and connectors should also be checked first. The symptom can also show up as a hunting idle.
What is checked first when the W140 ASR limp mode comes on?
1. Check the brake light switch. 2. Check the ASR circuit fuses; there are five 10 A fuses, and one can blow, for example during a battery change. 3. Check the throttle body and engine wiring harness connectors and the condition of the wires. 4. Make sure the battery and alternator are charging properly.
Does the W140 ASR light go out when the power is cut or the battery is disconnected?
Sometimes. If simply switching off the power does not turn the light off, disconnecting the battery terminal for about 10 minutes may reset it. If the fault is still present, the light comes on again, so the cause still has to be found: sensor, fuse, connector or ground.