P0170 - Fuel Trim Malfunction 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 notes
Dirty air filter, air filter housing or Mass Air Flow (MAF) sensor, or faulty MAF sensor are common causes for the P0170 code.
When is the code detected?
Fuel injection system does not operate properly or the amount of mixture ratio compensation is not correct
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Excessive Fuel Consumption
P0170 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).

P0170 Information for specific makes
P0170 AUDI
Fuel Trim Bank 1
P0170 BMW Fuel Trim Bank 1
P0170 CHRYSLER Fuel Trim Malfunction Bank 1
P0170 DODGE Fuel Trim Malfunction Bank 1
P0170 HYUNDAI Fuel Trim Bank 1
P0170 INFINITI Fuel Trim Malfunction Bank 1
P0170 JEEP Fuel Trim Malfunction Bank 1
P0170 KIA Fuel Trim Bank 1 Too Rich Or Lean
P0170 MAZDA Bank 1 Adaptive Fuel Table At Calibrated Limit
P0170 MERCEDES-BENZ Fuel Trim Malfunction Bank 1
P0170 MITSUBISHI Fuel Trim Malfunction Bank 1
P0170 NISSAN Fuel Trim Malfunction Bank 1
P0170 VOLKSWAGEN Fuel Trim Bank 1
P0170 BMW Fuel Trim Bank 1
P0170 CHRYSLER Fuel Trim Malfunction Bank 1
P0170 DODGE Fuel Trim Malfunction Bank 1
P0170 HYUNDAI Fuel Trim Bank 1
P0170 INFINITI Fuel Trim Malfunction Bank 1
P0170 JEEP Fuel Trim Malfunction Bank 1
P0170 KIA Fuel Trim Bank 1 Too Rich Or Lean
P0170 MAZDA Bank 1 Adaptive Fuel Table At Calibrated Limit
P0170 MERCEDES-BENZ Fuel Trim Malfunction Bank 1
P0170 MITSUBISHI Fuel Trim Malfunction Bank 1
P0170 NISSAN Fuel Trim Malfunction Bank 1
P0170 VOLKSWAGEN Fuel Trim Bank 1