OBD-II code · Powertrain (generic)
P0170 Fuel Trim Malfunction (Bank 1)
The ECU detects that short-term and long-term fuel trim values on bank 1 are outside acceptable limits. Engine cannot maintain stoichiometric mixture — typically a vacuum leak, fuel pressure issue, or failing MAF/O2 sensor.
Is it safe to drive with P0170?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyVacuum leak (intake gasket, hose, PCV)
- PossibleFuel pressure too low or too high
- PossibleMAF sensor reading drifted
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Intake System, Fuel Pressure Regulator, Mass Air Flow Sensor, Oxygen Sensor B1s1
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.