OBD-II code · Chassis
C0784 Trailer Brake Force Sensor Circuit Malfunction
The integrated trailer brake controller has detected an electrical fault in the brake force sensor circuit. Proportional trailer brake control is disabled — the controller defaults to a manual or fixed-gain mode.
Is it safe to drive with C0784?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyTrailer brake force sensor failed
- PossibleWiring or connector fault
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Trailer Brake Controller, Brake Force Sensor, Sensor Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.