P2245 O2 Sensor 1/1, 2/1 Reference Voltage Circuit Low

P2245 code - The Oxygen sensors (O2 sensor) are used for fuel control and catalyst monitoring. Each O2 sensor compares the oxygen content of the surrounding with the oxygen content of the exhaust stream. When the engine is started, the powertrain control module (PCM) operates in an open loop mode, ignoring the o2 sensor signal voltage while calculating the air to fuel ratio. The heating elements inside each O2 sensor heats the sensor to bring the sensor up to operating conditions faster. This allows the system to enter closed loop earlier and the PCM to calculate the air to fuel ratio sooner. While the engine runs, the O2 sensor heats up and begins to generate a voltage within a range of 0-1,275mV. Once suffient O2 sensor voltage fluctuation is observed by the PCM, closed loop is entered. The PCM uses the O2 sensor voltage to determine the air to fuel ratio. An O2 sensor voltage that increases toward 1,000 mV indicates a rich fuel mixture. An O2 sensor voltage that decreases toward 0 mV indicates a lean fuel mixture.

When monitored this DTC continuously after 15 seconds of engine runtime, no O2 sensor heater DTCs present and battery voltage greater than 10.4 Volts. Set condition the oxygent sensor reference voltage is below 0.9 volt for 60 seconds. The DTC will set as pending after one trip and active after two trips. Three good trips to turn off the MIL.

Possible causes P2245 code

- O2 sensor return circuit shorted to ground
- O2 sensor
- Powertrain Control Module (PCM)

Diagnostic test P2245 code

Step 1. Active DTC
The most likely cause of this DTC is O2 sensor return circuit shorted to ground. Ignition on, engine not running, with the scan tool select view DTCs. Copy DTC and freeze frame information. Start the engine allow the engine to reach normal operating temperature. Monitor the scan tool for at least two minutes, with the scan tool select view DTCs.

Is the status active for this DTC?

Yes, go to step 2.
No, perform the PCM intermittent condition.

Step 2. O2 sensor return circuit shorted to ground
Turn the ignition off disconnect the PCM harness connector. Disconnect the O2 sensor 1/1 harness connector, disconnect the O2 sensor 2/1 harness connector. Measure the resistance between ground and the O2 sensor return circuit reference voltage circuit at the O2 sensor 1/1 or 2/1 harness connector.

Is the resistance below 10k Ohms?

Yes, repair the O2 sensor return circuit for a short to ground.
No, go to step 3.

Step 3. O2 sensor 1/1 or 2/1
Turn the ignition off, reconnect the PCM harness connector. Ignition on, engine not running. With the scan tool, monitor the O2 sensor 1/1 and 2/1 voltage. Connect  a jumper wire between the O2 sensor 1/1 signal circuit and the O2 sensor return circuit in the O2 sensor 1/1 harness connector. Repeat step 5 for the O2 sensor 2/1 signal circuit.

Is voltage between 2.3 and 2.7 volts with the jumper wire installed?

Yes, verify that there is good pin to terminal contact in the O2 sensors and Powertrain Control Module connectors. Replace the O2 sensor not indicating the specified voltage of no problems were found with the connections.

No, remove the jumper wire before continuing, go to step 4.

Step 4. Check related PCM and component connections

Share this post