P2A83: Alternative Fuel Pump B Compression Stroke Valve Control Circuit/Open

P2A83 reports an open or otherwise faulty control circuit at the compression stroke valve of alternative fuel pump B. Whether a second pump exists depends on the layout: in Westport's patent US8726785B2, two LNG vessels each carry their own hydraulically driven pump, while Caterpillar's multi-element pump splits one unit into several separately switched elements. Either way, pump B's valve no longer admits drive oil, and its share of LNG delivery is lost. On a two-tank truck this can leave fuel stranded in the tank that pump B serves. The meaning of the letter B is not public, and no manufacturer documents P2A83. Where the valves are identical, swapping a connector with a neighbour shows whether the fault follows the coil.

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

Warning lamp on
LNG in one tank cannot be used
Reduced power under high load

Most likely causes

Open wire or loose connector at valve B
Solenoid coil of valve B open
Output stage for valve B faulty

What to check, in order

Start with the simplest. You can tick off each step.

If you smell gas, shut off the supply, ventilate and do not start the engine
Check the continuity of the wire between the component and the control module.
Read the codes with a compatible scanner
Check the connectors and wiring of the component indicated
Leave any work on the gas circuit to an authorized shop

Good to know

Repair difficulty: hard
It can trigger limp mode.
It affects emissions.

What each character of P2A83 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
A: Hybrid or air and fuel
83: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2A83?

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 P2A83?

The most common causes are: open wire or loose connector at valve B; solenoid coil of valve B open; output stage for valve B faulty.

Related codes

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.