What it means
The alternative fuel tank select valve A control circuit signal is lower than expected.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Alternative fuel tank select valve A is controlled through an electrical circuit that operates the valve for tank selection. The control module sets P2A93 when it detects a lower-than-expected signal in valve A's circuit, which can result from a short to ground, a shorted coil, or a poor terminal connection.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in valve coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or alternative-fuel system warning light, if equipped
- Difficulty switching fuel tanks
- Loss of power or stalling
How to diagnose it
- Record freeze-frame data and check live data to confirm the fault is associated with valve A's control command.
- Inspect valve A's connector for corrosion, moisture, loose terminals, or signs that pins are touching ground.
- Check the valve A control wire for chafing or a short to ground, paying attention to areas where the harness contacts the body.
- With the circuit isolated as specified by the manufacturer, test valve A's coil for an internal short and compare with the manufacturer's specification.
- If the fault remains, measure the control circuit at the module and valve connectors using the wiring diagram to locate where the signal drops.
Common fixes
- Clean or replace corroded terminals at valve A's connector.
- Repair the control wire where it is shorted to ground.
- Replace valve A if its coil is internally shorted.
- Repair damaged harness sections or connector terminals that pull the circuit signal low.
Can I keep driving?
Avoid relying on a tank change while valve A's circuit fault is active, and stop safely if the engine loses power or stalls. A low control signal can prevent reliable fuel selection.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.