P0739TCM Engine Speed Output Circuit High
- Generic OBD-II code · Powertrain
- How the car detects it
- Some transmission modules pass an engine speed signal on to other devices such as a tachometer over a wire of their own. CARB requires output circuits to be checked. No manufacturer document available to us uses P0737–P0739 – engine speed is shared over CAN today; the description follows CARB and the engine module's own speed output (P0654), which sends, for example, two pulses per revolution. P0739 means this output is too high, typically shorted to positive or, depending on the driver, open, so it can no longer switch to ground. The opposite is P0738, the general fault P0737. A tachometer or dependent display then reads nothing or full scale, while driving is usually unaffected.
- What you may notice
- Tachometer shows nothing or full scale
- Warning lamp depending on manufacturer
- Usually no effect on driving
- Likely causes
- LikelyOutput wire shorted to positive or open
- PossibleReceiver faulty
- PossibleConnector corroded
- RareDriver stage in the transmission module faulty
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.