VOLVO
ECM-181A - Air conditioning (A/C) pressure sensor. Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsS40 (1996–2004), V40 (1996–2004)
Show models by year and engine (2)
What does this fault code mean?
The ECM monitors the signal from the air conditioning pressure sensor. If the signal is faulty, too high or too low, the fault code is set. The cause may be too little refrigerant, a leak or a defective A/C pump.
Possible causes
- Signal wire shorted to voltage
- Defective A/C pressure sensor
- Signal wire shorted to ground
- Open circuit in the signal wire
- Incorrect refrigerant level
- Leak in the A/C system
What you can do
- 1Cars without A/C always show this fault code. If your car has no A/C, the code can be ignored
- 2Switch off the ignition and check that the A/C pressure sensor connector is firmly seated and free of oxidation
- 3Check that the A/C system has refrigerant, since a wrong level gives a faulty pressure reading
- 4Check the A/C system for leaks and damage. If the fault remains, have a workshop check the A/C pump and the pressure sensor
Symptoms you may notice1
- The air conditioning does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.