P2A9C: Alternative Fuel Tank Select Valve C Control Circuit High

P2A9C reports a control voltage at select valve C above the level the commanded state permits. The usual reasons are an interrupted coil or wire on a valve the module switches to ground, which leaves supply voltage on the line, or a foreign voltage fed in from a damaged neighbouring wire. Valve C then ignores commands. In a staged strategy like the one Cespira patented, where the controller moves between supplies as their pressures drop below set limits, the step involving vessel C is lost, so its content is either never tapped or cannot be shut out of the sequence. Range falls and the engine may switch to its other fuel sooner. No manufacturer publishes P2A9C. Compare coil resistance with valves A and B where they are identical.

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
Third vessel never drawn, range reduced
Earlier change to the other fuel

Most likely causes

Open coil or wire on ground-switched valve C
Foreign voltage from a damaged neighbouring wire
Corroded terminals at valve C

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 can trigger limp mode.
It affects emissions.

What each character of P2A9C means

P: Powertrain: engine and transmission
2: Generic code: same on every make
A: Hybrid or air and fuel
9C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2A9C?

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 P2A9C?

The most common causes are: open coil or wire on ground-switched valve C; foreign voltage from a damaged neighbouring wire; corroded terminals at valve C.

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.