VOLVO
ECM-400D - Three-way catalytic converter (TWC) efficiency, bank 1. Signal too low
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module has found that the efficiency of the catalytic converter on bank 1 deviates too much from normal, with the signal registered as too low. The code is set while driving under certain conditions. The cause may be misfiring, a leak, faulty fuel pressure, uneven compression or a damaged catalytic converter.
Possible causes
- Misfiring
- Leakage in the intake system
- Leakage in the exhaust system
- Faulty fuel pressure
- Uneven compression
- Damaged catalytic converter
What you can do
- 1Look for leaks in the intake system and the exhaust system, for example at hoses, joints and gaskets
- 2Check whether there are codes for misfiring alongside this one, and deal with those first
- 3Check the spark plugs and ignition coils for damage and moisture, since misfiring can cause the same fault
- 4Have a workshop check fuel pressure, residual pressure and compression with diagnostic equipment
- 5If the fault remains after this: have a workshop try a new oxygen sensor and then a new catalytic converter
Symptoms you may notice1
- Malfunction indicator lamp is lit
What the fault can affect1
- Rear oxygen sensor control is switched off
General guidance for car owners. Diagnosis on the car can point to a different cause.