Faulty transmission power relay, such as worn contacts or a sticking coil; Blown fuse or fusible link supplying the relay; Corroded, loose, or damaged wiring or connectors in the relay sense circuit; Poor ground connection for the relay or TCM; Failed transmission control module (TCM) internal driver or sense circuit; Water intrusion or physical damage to the relay or wiring harness; Voltage drop due to high resistance in the circuit, often from corrosion

DTC codes / P08xx · Transmission / P0889

P0889TCM Power Relay Sense Circuit Range/Performance

Q: What does code P0889 mean?

TCM Power Relay Sense Circuit Range/Performance. P0889 indicates that the transmission control module (TCM) has detected an out-of-range or performance fault in the power relay sense circuit, which monitors the voltage supplied to the TCM through the transmission power relay. The TCM expects a specific voltage signature when the relay is energized and de-energized, and this code sets when the signal falls outside the expected range or does not transition correctly.

P0889 indicates that the transmission control module (TCM) has detected an out-of-range or performance fault in the power relay sense circuit, which monitors the voltage supplied to the TCM through the transmission power relay. The TCM expects a specific voltage signature when the relay is energized and de-energized, and this code sets when the signal falls outside the expected range or does not transition correctly.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light or transmission warning light, often with no other symptoms
Transmission may enter limp mode, limiting gear selection to one or two gears
Harsh or delayed shifts, or failure to shift at all
No power to the transmission control module, resulting in a no-start or stall condition
Intermittent electrical issues such as flickering lights or erratic gauge behavior
The vehicle may fail to start or may stall shortly after starting

Common causes, most likely first

Faulty transmission power relay, such as worn contacts or a sticking coil
Blown fuse or fusible link supplying the relay
Corroded, loose, or damaged wiring or connectors in the relay sense circuit
Poor ground connection for the relay or TCM
Failed transmission control module (TCM) internal driver or sense circuit
Water intrusion or physical damage to the relay or wiring harness
Voltage drop due to high resistance in the circuit, often from corrosion

How to diagnose and fix it

Verify battery voltage and condition, as a weak battery can cause false relay codes
Check all fuses and fusible links related to the transmission power relay and TCM
Inspect the relay and its socket for corrosion, tightness, and signs of overheating
Perform a voltage drop test on the relay sense circuit to identify high resistance
Test the relay by swapping with a known-good relay of the same part number or by bench testing
Check ground connections for the relay and TCM for cleanliness and tightness
If all external circuits test good, diagnose the TCM and replace if necessary

Relay Sense Circuit Diagnostics You Should Not Skip

A faulty relay can test fine when bench-tested but fail under load or temperature changes, so always perform a loaded voltage drop test.
The sense circuit often shares a ground with other components, and a poor ground can cause this code without any relay fault.
Intermittent P0889 codes are frequently caused by chafed wiring that only shorts when the vehicle is in motion or over bumps.
Some vehicles use a solid-state relay integrated into the TCM, making the TCM itself the most likely cause after wiring checks.
A weak battery or charging system issue can set this code because the TCM expects a stable voltage range on the sense circuit.

Can I keep driving with P0889?

If the vehicle drives normally, you can drive cautiously to a repair shop, but avoid long trips or heavy loads. If the transmission is in limp mode or the engine stalls, stop driving and have the vehicle towed to prevent damage or unsafe conditions.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.