P2A43: Alternative Fuel Tank B Pressure Sensor Circuit Low

P2A43 is stored when the signal of the tank B pressure sensor drops below its lower electrical limit, a level that no real tank pressure produces. The usual reasons are a signal wire grounded against the frame, a missing 5 V reference or an internal short in the sensor. For the tank A sensor, TransEco's AFCM list puts exactly these faults under its Low code, with a substitute value of 3600 psi and the lamp switched on in both dedicated and bi-fuel setups. Because a low signal looks like an empty cylinder, the gauge may drop to zero and tank B may be locked out although it still holds gas. No manufacturer documents P2A43 itself. Ford's 2014 Boss 302S table carries the tank A version P01A0 as a lamp code, a sign that the family is treated as emission-relevant.

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

Check engine light
Gauge drops to empty for tank B
Less usable gas range

Most likely causes

Signal wire shorted to ground
5 V reference open or pulled down by another sensor
Internal short in the tank B sensor

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
With the connector unplugged, check whether the signal wire is making contact with ground.
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 affects emissions.

What each character of P2A43 means

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

Frequently asked questions

Can I keep driving with code P2A43?

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 P2A43?

The most common causes are: signal wire shorted to ground; 5 V reference open or pulled down by another sensor; internal short in the tank B sensor.

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.