Powertrain, generic (extended)

P2A63 Alternative Fuel Tank B Level Sensor Circuit Intermittent/Erratic

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

Fuel slosh makes any level reading wobble a little, and modules filter that out. P2A63 goes further: the tank B level signal drops out or jumps in steps no filter can explain, then returns to normal. Contacts at the sender are the main suspect, since the tank sits low on the chassis and is exposed to spray and road salt; a cable pinched by a tank strap or a Hall module losing contact in its housing are other options. Rochester presents its contact-free Hall design as more reliable than senders with a sliding wiper, and a worn wiper track is indeed a classic source of such jumps. No manufacturer documents P2A63; on petrol vehicles the counterpart is P2069 for the second sender. Watch the level reading while rocking the vehicle and flexing the harness.

Likely causes

Corroded contacts at the tank B sender from road spray

Cable pinched by a tank strap

Worn wiper track or loose Hall module in the sender

Symptoms

Gas gauge for tank B jumps or briefly drops
Check engine light from time to time
Range display unsteady

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–600

Time0.5–3 h

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

Parts involved

alt fuel tank b level sensorwiring harnessafcm

References: law.cornell.edu, rochestersensors.com.