P0170 Citroen Fuel Trim Bank 1

Possible causes

– Intake air leaks
– Faulty front heated oxygen sensor
– Ignition misfiring
– Faulty fuel injectors
– Exhaust gas leaks
– Incorrect fuel pressure
– Lack of fuel
– Faulty Mass Air Flow (MAF) sensor
– Incorrect Positive Crankcase Ventilation (PCV) hose connection

Tech description

Dirty air filter, air filter housing or Mass Air Flow (MAF) sensor, or faulty MAF sensor are common causes for the P0170 Citroen code.

What about the obd code?

Fuel injection system does not operate properly or the amount of mixture ratio compensation is not correct

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Excessive Fuel Consumption

P0170 Citroen Description

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.

In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the Malfunction Indicator Light (MIL) (2 trip detection logic).