P2A8E reports that alternative fuel pump A no longer delivers what it should, a mechanical or hydraulic fault rather than an electrical one. Such pumps move liquid fuel, typically LNG out of a cryogenic tank. A patent application now held by Cespira, US20080302111A1, shows how a controller can judge them from the delivery line pressure alone: each time the pump is commanded on, pressure has to climb from a lower to an upper set point within a known range of slopes. A clearly flatter rise means lost volumetric efficiency, and a falling pressure means the pump cannot even keep up with the engine. The document names worn piston seals, leaking static seals or check valves, dirt in the fuel and a weak hydraulic drive as causes. No manufacturer publishes P2A8E or its limits.
High severity. Can I keep driving?If you smell gas, do not keep driving or start the engine: move away and call for assistance. With no smell, drive moderately to an authorized shop.
Symptoms
- Malfunction lamp on
- Power loss at high load, gas pressure sagging
- Pump runs noticeably longer to refill the accumulator
- Engine switched to reduced output or diesel-only operation
Most likely causes
- Worn dynamic piston seals in pump A
- Leaking inlet or outlet check valve of pump A
- Hydraulic drive of pump A delivering too little force or speed
- Impurities in the fuel passing the filter and damaging the pump
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P2A8E means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- A: Hybrid or air and fuel
- 8E: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2A8E?
If you smell gas, do not keep driving or start the engine: move away and call for assistance. With no smell, drive moderately to an authorized shop.
What causes code P2A8E?
The most common causes are: worn dynamic piston seals in pump A; leaking inlet or outlet check valve of pump A; hydraulic drive of pump A delivering too little force or speed.
Related codes
- P2A8FAlternative Fuel Pump B Performance
- P2A90Alternative Fuel Pump C Performance
- P2A7FAlternative Fuel Pump A Compression Stroke Valve Control Circuit/Open
- P2A80Alternative Fuel Pump A Compression Stroke Valve Control Circuit Range/Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.