P278AKick Down Switch Circuit
- Generic OBD-II code · Powertrain
- How the car detects it
- P278A is the general circuit fault of the kickdown switch, the contact at the end of accelerator pedal travel that asks the transmission for the lowest possible gear. No manufacturer documents P278A publicly. Many current cars no longer have an electrical switch: Mazda states for the 2024 CX-90 that its kickdown element only adds a felt detent and sends no signal, the pedal position sensor alone deciding. Where a real switch or message exists, the transmission control checks it; Eaton's Endurant HD gearbox logs fault 167 if the kickdown message from the pedal is missing or invalid for 5 s. CARB requires circuit monitoring for such inputs. P278B to P278E name the fault type more precisely. Without the signal, full-throttle downshifts may be weaker or later.
- What you may notice
- No forced downshift at full throttle
- Reduced acceleration when overtaking
- Likely causes
- PossibleKickdown switch in or under the pedal defective
- PossibleWiring or connector of the pedal module damaged
- RareKickdown message missing on the data bus (networked designs)
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.