OBD-II Generic Error Code P0891: How to Fix It

Q: Can I drive with error code P0891?

It's not recommended. The code indicates a high voltage issue in the TCM power relay circuit, which can cause transmission shifting problems or limp mode. Have it diagnosed promptly to avoid further damage.

Q: What does TCM power relay sense circuit high mean?

It means the TCM is detecting a higher-than-normal voltage on the circuit that monitors the power relay's output. This could be due to a short-to-voltage, faulty relay, or a problem within the TCM itself.

Q: How do I clear P0891 after fixing?

Use an OBD2 scanner to clear the code. Alternatively, disconnect the battery for 10 minutes, but this may erase other learning data. Drive the car through a drive cycle to confirm the code doesn't return.

Q: Can a bad battery cause P0891?

Yes, a weak or overcharging battery can cause voltage spikes that trigger this code. Test the battery and charging system if voltage irregularities are suspected.

Q: Is P0891 a common error?

It's less common than other transmission codes but can appear in various makes. It is often related to relay or wiring issues rather than a TCM failure.

Abstract

Error code P0891 indicates the Transmission Control Module (TCM) has detected a high voltage condition in the power relay sense circuit. This often points to a faulty relay, wiring issues, or a failing TCM. The severity is medium; driving with this code may cause transmission shifting problems or limp mode.