Manufacturer-specific code

This code means different things on different makes. Find yours below.

• Ford

  Lack of upstream oxygen sensor switching: sensor indicates lean (bank 1)

  The front oxygen sensor stays lean and does not switch, even though fuel control is adding fuel.

  Likely causes, most likely first

  1. 01Air leak in the intake or crankcase ventilation
  2. 02Dirty mass air flow (MAF) sensor
  3. 03Low fuel pressure or a clogged fuel filter
  4. 04Exhaust leak before the sensor
  5. 05Aged front oxygen sensor

  Severity: Caution: get it checked soon · DIY with tools and some experience