P0884
TCM Power Input Signal Intermittent
- Severity
- High
- Driving
- Drive only to a garage
The transmission module's supply voltage is dropping out or fluctuating intermittently. The transmission may behave perfectly for days and then shift harshly or drop into limp mode. Intermittent supply faults are usually a connection - a terminal, an earth or a relay - rather than a failed component.
Possible causes
- CommonLoose or corroded battery terminal
- CommonCorroded earth point
- CommonFailing relay with worn contacts
- PossibleChafed or fatigued supply wiring
- PossibleFailing alternator with an intermittent output
- PossibleBattery on the point of failing
What you might notice
- Occasional limp mode that clears after a restart
- Shift quality varying between journeys
- Momentary flicker of the dashboard lights
- Check engine light coming and going
What to check, in order
- Wiggle-test the battery terminals and the main earth straps with the engine running while watching voltage on the live data screen.
- Have the battery load tested. A battery on the way out produces intermittent faults across the whole vehicle before it fails outright.
- Swap the supply relay for an identical one elsewhere in the box and see whether the fault follows it.
- Perform a voltage drop test on the supply and earth circuits.
- Record the freeze frame data. Knowing what the voltage was when the code set often identifies the problem straight away.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Transmission
P0800P0801P0802P0803P0804P0805P0806P0807P0808P0809P0810P0811P0812P0813P0814P0815P0816P0817P0818P0819P0820P0821P0822P0823P0824P0825P0826P0827P0828P0829P0830P0831P0832P0833P0834P0835P0836P0837P0838P0839P0840P0841P0842P0843P0844P0845P0846P0847P0848P0849P0850P0851P0852P0853P0854P0855P0856P0857P0858P0859P0860P0861P0862P0863P0864P0865P0866P0867P0868P0869P0870P0871P0872P0873P0874P0875P0876P0877P0878P0879P0880P0881P0882P0883P0884P0885P0886P0887P0888P0889P0890P0891P0892P0893P0894P0895P0896P0897P0898P0899