Powertrain, generic (extended)

P20FB Reductant Pump B Control Performance/Stuck Off

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P20FB is the functional check of reductant pump B: its circuit is electrically sound, yet the pump does not reach the commanded state or stays off when it should be running. No public threshold exists for pump B. For pump A, Ford's 2023 diesel summary flags P208B when pump speed misses its setpoint by more than 300 rpm or the speed control sits at its limit for 30 seconds, which shows the principle. FCA names P20FB Reductant Pump 2 Control Performance and has listed it in a series of PCM reflash bulletins for the 3.0L EcoDiesel in Ram 1500, Wrangler and Gladiator (2020–2021, e.g. 18-028-21 and 18-002-23), so on those trucks a software update comes before any parts. Genuine causes are a worn, frozen or blocked pump or a clogged filter.

Likely causes

Outdated PCM software (FCA 3.0L EcoDiesel, reflash bulletins)
Pump B worn, seized or blocked by crystallised fluid
Frozen DEF or failed tank heating in cold weather
Clogged pump filter or restricted lines

Symptoms

  • Malfunction indicator lamp on
  • DEF system warning, possibly with countdown to restart lockout
  • Code returns mainly after cold starts or long parking

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time0.5–4 h

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

Parts involved

reductant pump

Related codes

P20FAP20FCP20FDP208B

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