P2A84 code meaning
Alternative Fuel Pump B Compression Stroke Valve Control Circuit Range/Performance
Powertrain system Generic code P2Axx codes Check engine light
What P2A84 means
P2A84 is set when pump B's compression stroke valve is electrically sound yet the pump does not respond as commanded. A controller that drives several pumps or elements in turn can compare them: in Caterpillar's multi-element patent, flow results from how often the elements are fired and how long each waits, so an element adding less pressure per command than its neighbours stands out. A slow spool, contaminated oil, internal leakage past the spool or worn plunger seals on the cryogenic side can all reduce pump B's output. With two tank pumps as in Westport's patent, the pressure behaviour before and after a switchover can also be compared. No manufacturer publishes P2A84. Check oil condition and compare delivery with pump A.
P2A84 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1.5 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P2A84
- Warning lamp after several drive cycles
- Lower delivery from one tank or element
Common causes of P2A84
- Most likelySpool of valve B slow or leaking internally
- PossibleContaminated hydraulic oil
- Less likelyWorn plunger seals on the cryogenic side of pump B
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 P2A84 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. |
| 84 | The exact fault in that area. |
What to do next
- Note P2A84 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 P2A84
What does P2A84 mean?
P2A84 means "Alternative Fuel Pump B Compression Stroke Valve Control Circuit Range/Performance". P2A84 is set when pump B's compression stroke valve is electrically sound yet the pump does not respond as commanded. It is a generic code, so it means the same on every make.
Is it safe to drive with P2A84?
Drive gently and only to a workshop. With P2A84 the car can go into limp mode (reduced power) to protect itself.
Will P2A84 fail an emissions test?
Yes, it can. P2A84 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 P2A84 to fix?
Difficulty: workshop only. A typical repair takes 1.5 to 6 hours of work. This is a job for a workshop.
Will P2A84 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.