Powertrain, generic (extended)

P2A43 Alternative Fuel Tank B Pressure Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

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

Symptoms

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

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–700
Time1–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

alt fuel tank b pressure sensorwiring harnessafcm

Related codes

P2A41P2A44P2A42P01A0

References: law.cornell.edu, http:, performanceparts.ford.com.