P224C: Alternative Fuel Tank Shutoff Valve A Control Circuit/Open

P224C points to an open or otherwise faulty control circuit of shutoff valve A, the solenoid on a CNG or LPG tank that releases gas only when the engine runs on the alternative fuel. Such valves are normally closed. GM's 2015 bi-fuel Impala (bulletin PI1330) fits a high-pressure cut-off solenoid to the tank and energizes it in CNG mode while the engine cranks or runs; Ford's 2003 bi-fuel CNG documentation feeds its tank valve through the inertia switch and the ALT fuel relay. Neither publishes codes for the valve. No maker documents P224C publicly, and the CNG upfitter TransEco even files an open circuit under P224E. With the valve dead, bi-fuel cars carry on with gasoline; dedicated gas vehicles may not start.

Symptoms

• Check engine light
• Vehicle will not switch to gas operation or falls back to gasoline

Most likely causes

• Broken wire or unplugged connector at the tank valve
• Solenoid coil of the valve open
• Supply interrupted by relay or tripped inertia switch

What to check, in order

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

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

Good to know

• Repair difficulty: hard
• It affects emissions.

What each character of P224C means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 2: Fuel injection
• 4C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P224C?

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 P224C?

The most common causes are: broken wire or unplugged connector at the tank valve; solenoid coil of the valve open; supply interrupted by relay or tripped inertia switch.

Related codes

• P224DAlternative Fuel Tank Shutoff Valve A Control Circuit Performance/Stuck Off
• P224EAlternative Fuel Tank Shutoff Valve A Control Circuit Low
• P224FAlternative Fuel Tank Shutoff Valve A Control Circuit High
• P2A22Alternative Fuel Tank Shutoff Valve B Control Circuit/Open

Sources

• static.nhtsa.gov: MC 10114282 9999
• static.nhtsa.gov: INRD PE08063 33504P
• transecoenergy.com: DTC List
• law.cornell.edu: 13 CCR 1968.2

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.