P2A86 code meaning
Alternative Fuel Pump B Compression Stroke Valve Control Circuit High
Powertrain system Generic code P2Axx codes Check engine light
What P2A86 means
P2A86 is stored when pump B's compression stroke valve circuit shows a higher voltage than its state allows, pointing to an interrupted coil, a broken return wire where the valve is switched on the ground side, or a short to the supply. The valve then rests in its drain position: drive oil bypasses pump B and its plunger stays retracted. On a two-tank layout as in Westport's patent, the controller may keep drawing from the other tank, so the truck runs on while the second tank's LNG cannot be used and slowly warms up. Because the pump performs no strokes, its usual hydraulic pressure signature disappears, which helps to confirm the diagnosis. No manufacturer documents P2A86. Check the coil, the plug and the supply feed.
P2A86 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2A86
- Warning lamp on
- One LNG tank is no longer emptied
- Shorter range on gas
Common causes of P2A86
- Most likelyOpen coil or broken wire at valve B
- PossibleControl wire shorted to supply voltage
- Less likelyCorroded terminals in the valve B plug
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alt fuel pump b compression stroke valveWiring harnessAfcm
What each part of P2A86 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| A | Area: hybrid propulsion. |
| 86 | The exact fault in that area. |
What to do next
- Note P2A86 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2A86
What does P2A86 mean?
P2A86 means "Alternative Fuel Pump B Compression Stroke Valve Control Circuit High". P2A86 is stored when pump B's compression stroke valve circuit shows a higher voltage than its state allows, pointing to an interrupted coil, a broken return wire where the valve is switched on the ground side, or a short to the supply. It is a generic code, so it means the same on every make.
Is it safe to drive with P2A86?
Drive gently and only to a workshop. With P2A86 the car can go into limp mode (reduced power) to protect itself.
Will P2A86 fail an emissions test?
Yes, it can. P2A86 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2A86 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P2A86 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.