P2A85Alternative Fuel Pump B Compression Stroke Valve Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2A85 means the drive output for pump B's compression stroke valve reads too low for its commanded state. Typical are a control wire chafed through to the frame, which can keep the solenoid energised even when the controller wants it off, or a coil with shorted windings that draws excessive current. A valve stuck in the fill position leaves pump B's plunger parked at full extension; the pump stops delivering, and pressurised oil remains on its drive side. Caterpillar's six-element example can partly make up for this with the remaining elements, whereas a two-tank system loses the second tank's supply. No manufacturer publishes P2A85. Compare the measured coil resistance with that of an identical A or C valve.
- What you may notice
- Warning lamp on
- Pump B delivers nothing, reduced power or range
- Likely causes
- LikelyControl wire of valve B chafed through to the frame
- PossibleCoil of valve B with shorted windings
- RareOutput stage for valve B shorted
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.