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 less than .37 volt and ECON status light will go off. Manipulate ground to engine circuit No. 413, and look a loose ground eyelet or ground eyelet installed at wrong location. If lean engine operation is suspected, perform PFI SYSTEM CHECK. If oxygen sensor circuit seems to be okay, go to CHART A-9, OXYGEN SENSOR DIAGNOSIS.

Fig 1: PCM Code EO44, Schematic, Right O2 Sensor Lean Signal
G91I09354
RENDER: 1.0x

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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.