Here is info from Vadis. Use lower limit info.


Diagnostic trouble code (DTC) information

Condition

The control module receives information from the heated oxygen sensor (HO2S) about the fuel / air mixture when idling at both the lower and upper part-load range. If the fuel / air mixture deviates from λ=1, the short-term fuel trim will compensate for this by adjusting the injection time so that λ=1 is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. Diagnostic trouble code (DTC) ECM-261A will be stored when the long-term trim must be adjusted to almost maximum in the lower part load area.


Substitute value
none


Possible source

Upper limit:
-intake air leakage
-exhaust system air leakage
-low fuel pressure
-defective heated oxygen sensor (HO2S)
Lower limit:
-intake air leakage
-high fuel pressure
-leaking injectors
-defective mass air flow (MAF) sensor
-contaminated engine oil
-oil level too high
-defective heated oxygen sensor (HO2S)


Fault symptom[s]
-none