Code 13 - Open Oxygen Sensor Circuit

Code 13 will set with engine at operating temperature at least 2 minutes after engine start. The ECM must see: O2 signal voltage steady, between .35-.55 volt for more than 1 minute, or see TPS signal at more than 6% (.8-1.2 volt). Possible causes of a Code 13 are a faulty O2 sensor, faulty wiring or terminals, or a faulty ECM.

1. This test allows the ECM to confirm either open or closed loop operation using the "CHECK ENGINE" light.
2. This step verifies that no additional codes are stored and that Code 13 is intermittent.
3. This test simulates a lean exhaust. If the ECM and wiring are okay, the ECM will turn the "CHECK ENGINE" light off. Light will flash open loop at least 30 seconds after engine start. It is normal for the light to remain off for a longer period of time after engine start.

Fig 1: Code 13, Open Oxygen Sensor Circuit

Fig 2: Code 13, Open Oxygen Sensor Circuit