Powertrain, generic (extended)

P20FD Reductant Pump B Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P20FD indicates that the control line of reductant pump B sits too high, for instance shorted to battery voltage, so the controller can no longer regulate the pump properly. No limits are published for pump B. Ford's 2023 diesel summary sets the matching pump A fault (P208D) when pump voltage exceeds 16 V or controller current passes 5 A while the driver is on, confirmed within about 2 seconds, which is quicker than the 8 seconds used for open and low faults. Ford is the only maker that documents P20FD itself: 2023–2024 Super Duty and F-650/F-750 trucks with the 6.7L diesel can store it together with P20FA and P20FC, and the SSMs direct technicians to inspect connectors for moisture and corrosion. A pump that cannot be controlled ends DEF dosing until repaired.

Likely causes

Pump B control line shorted to battery or supply voltage
Moisture or corrosion bridging pins in the pump connectors
Internal electrical fault in pump B
Faulty output stage in the control module

Symptoms

  • Malfunction indicator lamp on
  • DEF system warning, dosing suspended
  • Countdown to restart lockout in the instrument cluster

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.5–3 h

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

Parts involved

reductant pumpwiring harness

Related codes

P20FAP20FBP20FCP208D

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