What it means
Voltage on the pressure sensor signal line of alternative fuel tank B is below the expected window. Wire shorted to ground or sensor short.
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
The AFCM reads the signal wire from the alternative-fuel tank B pressure sensor to estimate tank pressure. P2A43 sets when that signal falls below the expected electrical window, commonly because the signal is grounded, the sensor is internally shorted, or corroded pins disrupt contact. The resulting pressure indication may be inaccurate and alternative-fuel operation may be limited.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Alternative-fuel warning light
- Inaccurate tank pressure or fuel-level indication
How to diagnose it
- Record freeze-frame data and AFCM live data for tank B pressure, then note whether the reading is unusually low or fixed.
- Inspect the tank B sensor connector and harness for a signal wire touching ground, corrosion, loose pins, or damage.
- Check sensor connector contact and inspect for corrosion that could create high contact resistance.
- Test the signal circuit for a short to ground and check sensor power and ground against the manufacturer’s wiring diagram and specification.
- If the harness and connections pass, test the tank B pressure sensor for an internal short using the specified procedure.
Common fixes
- Repair a tank B pressure-sensor signal wire shorted to ground.
- Clean or repair corroded connector pins and restore secure contact.
- Replace the tank B pressure sensor if it fails the specified tests.
Can I keep driving?
The tank B pressure reading may be wrong and the AFCM may restrict alternative-fuel use. Use gasoline only if the vehicle runs normally on it, and avoid relying on the alternative-fuel gauge until the fault is fixed.
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.