Test TC-11A - O2S Stays Below Center (Lean) (DTC 51)

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, 1995 Dodge Caravan, and 1995 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS section at the end of this article.

Start engine. Allow engine to run until normal operating temperature is reached. Using scan tool, set engine speed to 1500 RPM and read Oxygen Sensor (O2S) voltage. If voltage is not always less than .5 volt, condition required to set DTC is not present at this time. Stop all tests and go to next step. If voltage is always less than .5 volt, go to step 3).
O2S STAYS BELOW CENTER (LEAN) DTC sets if O2S output voltage stays at less than .5 volt without changing for more than 8 minutes. Possible causes are: large vacuum leak, low fuel pressure, other engine sensor calibration failures, ignition system failure, O2S failure or fuel contamination. Go to TEST NTC-1A.
Using scan tool, check if O2S voltage is always zero volts. If O2S voltage is always zero volts, go to next step. If O2S voltage is not always zero volts, a condition causing engine to run lean is present. Go to TEST NTC-1A.
Using scan tool, stop all actuation tests. Turn ignition on with engine off. Disconnect O2S connector. Using scan tool, read O2S state. If O2S state is at center, replace O2S. Perform TEST VER-2.
If O2S state is not at center, turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Using scan tool in ohmmeter mode, check resistance of O2S connector signal circuit (Dark Green/White wire) on harness side.
If resistance is less than 5 ohms, repair short to ground in Dark Green/White wire. Perform TEST VER-2. If resistance is more than 5 ohms, replace PCM. Perform TEST VER-2.