Note On Intermittents

1991 Cadillac Seville STSSECTION Note On Intermittents

With engine running, manipulate oxygen sensor, PCM wiring, and connectors while observing PCM parameter ED33. If fault is induced, ED33 will jump to greater than .63 volt, and ECON status light will illuminate. Manipulate circuit No. 413 (ground to engine), and look a loose ground eyelet or ground eyelet installed at wrong location. If oxygen sensor circuit is okay or lean engine operation is suspected, perform PFI SYSTEM CHECK.

Fig 1: PCM Code EO43, Schematic, Left O2 Sensor Rich Signal
G91I09354
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.