P2A31: Alternative Fuel Tank Shutoff Valve E Control Circuit High

P2A31 closes the shutoff valve series with the high fault on valve E: the module measures voltage on the control wire where none should be. TransEco names a short to power and lights the MIL while the gas system continues; it prints P2A21 beside the code. Ford's Boss 302S list includes P2A31 without a MIL marker. In operation this can mean that cylinder E keeps supplying gas when the module wants it locked, for example after the inertia switch has tripped, the device through which Ford cut gas on its 2003 bi-fuel CNG vehicles. In the J2012 range the AFCM power relay codes follow from P2A32 onwards. P2A30 is the low-side code for the same valve, P2A2D the high fault on valve D.

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

Check engine light
Cylinder E not locked when it should be

Most likely causes

Valve E wire shorted to a voltage source
Driver for valve E in the module stuck on
Valve E fed from a wrong circuit after an upfit

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 sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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 affects emissions.

What each character of P2A31 means

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

Frequently asked questions

Can I keep driving with code P2A31?

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 P2A31?

The most common causes are: valve E wire shorted to a voltage source; driver for valve E in the module stuck on; valve E fed from a wrong circuit after an upfit.

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.