OBD-II · Engine and powertrain (P)
P1128
Manufacturer-specific code
Meaning by manufacturer
This code means different things on different makes. Find yours below.
Volkswagen, Audi, Seat, Skoda, Cupra
Long-term fuel trim (multiplicative) bank 1: system too lean
Bank 1 mixture adaptation has reached its lean correction limit in the part-load (multiplicative) range. The engine computer is adding fuel; possible reasons include incorrect air measurement, insufficient fuel delivery or a misleading lambda signal.
Likely causes, most likely first
- 01Mass air flow (MAF) sensor reading low (dirty or aged)
- 02Air leak between the MAF sensor and the throttle (split intake boot)
- 03Low fuel pressure: clogged fuel filter or weak fuel pump
- 04Exhaust leak before the front lambda sensor
- 05Front lambda sensor aged or contaminated
- 06Poorly calibrated LPG conversion (if fitted)
Severity: Caution: get it checked soon · DIY with tools and some experience