4. O2 Ground Circuit

Turn the ignition off.

Disconnect the PCM harness connectors.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the O2 Ground circuit from the O2 Sensor harness connector to the PCM harness connector.

Fig 1: Measuring Resistance Of O2 Ground Circuit

Courtesy of DAIMLERCHRYSLER CORP.

Is the resistance below 5.0 ohms?

Yes >> Replace the Oxygen Sensor. See FUEL SYSTEM article.
See POWERTRAIN VERIFICATION TEST - VER 2 .
No >> Check the O2 Ground circuit for damage, short to ground, open, or short to voltage. If OK, replace and program the Powertrain Control Module. See ELECTRONIC CONTROL MODULES article.
See POWERTRAIN VERIFICATION TEST - VER 2 .