P2A98: Alternative Fuel Tank Select Valve B Control Circuit High

P2A98 appears when the voltage on the control circuit of tank select valve B stays higher than the module allows for the commanded state. A ground-switched valve with an interrupted winding or lead shows this pattern, as does a wire that has picked up battery voltage. The valve will then not move on command, and the system keeps drawing from whichever vessel the resting valve connects. In Westport's two-vessel design with a single pump, that means one tank is used up and the second is never reached, so the engine runs short of gas while the gauge still shows reserve. CARB's heavy-duty rule expects such circuit faults to be detected and stored separately. No manufacturer publishes P2A98. A coil resistance check at the valve plug separates a dead coil from a wiring fault.

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
Second vessel never used, gas runs out early
Gauge shows reserve while power drops

Most likely causes

Interrupted winding or lead at valve B
Control line of valve B in contact with battery voltage
Corrosion at the valve B connector raising resistance

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 P2A98 means

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

Frequently asked questions

Can I keep driving with code P2A98?

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 P2A98?

The most common causes are: interrupted winding or lead at valve B; control line of valve B in contact with battery voltage; corrosion at the valve B connector raising resistance.

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.