Powertrain, generic · Fuel and air metering, auxiliary emission controls

P00FD Battery B State of Charge Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

'Battery B' here is not a hybrid high-voltage battery (those have codes from P0B27) but, in the only documented use by FCA/Stellantis, the 12 V auxiliary battery of the start-stop system. When the engine restarts automatically, a relay separates main and auxiliary battery so that the auxiliary one keeps the control units stable while the main battery cranks. The engine module sets P00FD if the auxiliary battery is disconnected on the first start, drops below about 8 V during an auto-start, or repeatedly falls below 10.3 V (counter reaches ten). Start-stop is then disabled; often it follows a jump start or many short trips. Whether the MIL comes on is not stated in the sources.

Likely causes

Auxiliary battery discharged or aged
Loose or corroded positive or ground connections at either battery
150 A fuse or fuse array in the power distribution centre open or poorly contacting
Battery separation relay stuck
Main battery faulty

Symptoms

  • Start-stop out of service, 'Service Start/Stop' message
  • Engine does not crank once
  • 'Service Shifter' message with electronic gear selector

Repair estimate

DifficultyEasyDIY possible
Parts and labour€0–250
Time0.3–1.5 h

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

Parts involved

auxiliary batterypower control relaybattery cablesfuses

Related codes

P2AF5P2AF6P0562P0563P0560

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.