What does fault code ECM-P209628 mean?

Diagnostic fault code details for ECM-P209628 (Volvo S60 (2011–), Volvo S60 (2011–), Volvo S80 (2007–)). Repair service at OBD Tuning.

VOLVO

ECM-P209628 - Post Catalyst Fuel Trim System Too Lean Bank 1. General Signal Failures. Signal bias level out of range / zero adjustment failure

System

Engine Control Module (ECM)

Volvo models this fault code applies to

Applies to the following models:

6 models

S60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V60 (2011–), V70 (2008–)

Show models by year and engine (11)

What does this fault code mean?

Although the code is named signal bias or zero adjustment failure, the two oxygen sensors give conflicting pictures of the mixture. The ECM compares the adaptation values of the front and rear sensors, and the code is set when they deviate too much. The fault may lie in the front or rear sensor circuit.

Possible causes

Leakage in the exhaust system
Oxygen sensor indicates an incorrectly lean mixture
Damaged oxygen sensor

What you can do

1Check the wiring to the oxygen sensors for damage, chafing and loose connectors
2If you have a diagnostic tool: read the oxygen sensor signals in live data with the engine running and see whether they differ more than they should
3Check the exhaust system for leaks, since air in the exhaust can give a wrong signal
4If the fault remains, have a workshop establish whether the engine control module has an internal fault

Symptoms you may notice1

Check engine warning lamp lights or behaves abnormally

What the fault can affect2

Oxygen sensor control is switched off
Catalytic converter diagnostics are switched off

General guidance for car owners. Diagnosis on the car can point to a different cause.