P2A7F: Alternative Fuel Pump A Compression Stroke Valve Control Circuit/Open

Hydraulically driven LNG pumps use solenoid valves to admit high-pressure oil to the drive side for the compression stroke and to vent it again for refilling. Caterpillar's patent US10060421B2 gives each of its six pumping elements, other counts being possible, a solenoid pilot that moves a spool between fill and drain positions; the controller sets timing and length of every stroke this way. P2A7F reports that pump A's compression stroke valve has an open or otherwise faulty control circuit. The valve then stays in its spring position and pump A no longer delivers. Which element or tank pump carries the letter A is not published, and neither is P2A7F itself. Check coil resistance and connector first.

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
Reduced LNG delivery and lower power
Gas pressure drops under load

Most likely causes

Open wire or loose connector at valve A
Solenoid coil of valve A burnt open
Output stage in the control module 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 P2A7F means

P: Powertrain: engine and transmission
2: Generic code: same on every make
A: Hybrid or air and fuel
7F: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2A7F?

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 P2A7F?

The most common causes are: open wire or loose connector at valve A; solenoid coil of valve A burnt open; output stage in the control module 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.