Dr2 - Code 51, (O2 Feedback System)
- Turn ignition off. Connect tachometer to engine. Disconnect Oxygen (O2) sensor. Connect one end of jumper wire to O2 sensor harness connector. Start engine and set speed to 2000 RPM. Touch other end of jumper wire to battery positive post and then to battery negative post.
- When jumper wire is touched to battery positive post, display on diagnostic readout box (DRB) should be "1" and engine speed should decrease. When jumper wire is touched to battery negative post, display on DRB should change to "0" and engine speed should increase. If display changes and engine speed responds as described, check for vacuum leaks and a partially blocked vacuum hose to MAP sensor. If okay, replace O2 sensor.
- If display and engine speed did not change, return engine to idle. Turn ignition off. Remove jumper wire. Disconnect logic module Blue connector. Connect ohmmeter to Blue connector cavity No. 21 and O2 sensor harness connector. There should be continuity. If there is no continuity, repair O2 sensor wire for an open circuit to logic module.
- If there is continuity, connect ohmmeter to O2 sensor harness connector and ground. There should be no continuity. If there is continuity, repair O2 sensor wire for a short to ground. If there is no continuity, replace logic module.