P278BKick Down Switch Circuit Range/Performance
- Generic OBD-II code · Powertrain
- How the car detects it
- P278B describes a kickdown switch whose state contradicts the pedal position. No manufacturer documents P278B publicly. The obvious cross-check is the accelerator pedal sensor: a switch reporting kickdown at part throttle, or staying open although the pedal is pressed to the stop, is implausible. Mazda's 2024 CX-90 bulletin shows how tight the link is, since there the pedal sensor alone defines kickdown and the mechanical detent only gives feel; on cars with a real contact, a worn detent, a misadjusted switch or a floor mat holding the pedal back can create exactly this mismatch. CARB asks for rationality checks on inputs like this. Unlike P278C and P278D the voltage itself is valid. Expect missing or unexpected kickdown shifts.
- What you may notice
- Kickdown missing at the pedal stop
- Unexpected downshift at part throttle
- Likely causes
- LikelyKickdown switch misadjusted or detent worn
- PossibleFloor mat or object preventing full pedal travel
- RarePedal position sensor offset so that both signals disagree
- Repair
- Easy · Often possible to do yourself.Typical cost: €0 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.