Powertrain
generic / SAE
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.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 70
Possible causes
- Vacuum leak (intake gasket, hose, PCV) high
- Fuel pressure too low or too high medium
- MAF sensor reading drifted medium
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 50–500 €
- Estimated time: 0.5–3 h
- Component: intake system
- Component: fuel pressure regulator
- Component: mass air flow sensor
- Component: oxygen sensor b1s1
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012