P20FC: Reductant Pump B Control Circuit Low

P20FC sets when the drive signal for reductant pump B reads too low, typically a ground fault on the line or a current draw beyond what the driver allows. Pump B has no published limits. For pump A, Ford's 2023 diesel summary reports the low fault (P208C) when pump current exceeds 5 A or the pump controller draws more than 15 A, checked with the driver off and confirmed after about 8 seconds; a similar logic is likely for pump B but undocumented. The only codegenau manufacturer evidence comes from Ford: 2023–2024 Super Duty and F-650/F-750 6.7L trucks may log P20FC alongside P20FA and P20FD, and the SSMs point to wet or corroded connectors first. Unlike P20FA, the circuit is not open but pulled down; unlike P20FD it is not stuck high.

Medium severity. Can I keep driving?Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

Symptoms

Malfunction indicator lamp on
DEF system warning and reduced or no reductant dosing
Restart lockout after the inducement countdown if left unrepaired

Most likely causes

Chafed wire shorting the pump B control line to ground
Water ingress or corrosion in the pump connectors
Pump B motor drawing excessive current (internal short or tight motor)
Faulty output stage in the control module

What to check, in order

Start with the simplest. You can tick off each step.

Check the AdBlue/DEF level and quality, and do not add additives or water
With the connector unplugged, check whether the signal wire is making contact with ground.
Look for white crystals around the injector and the tank
Check connectors and heaters with the scanner
Run the dosing test available on your diagnostic tool
Replace parts only when the test points to that component

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P20FC means

P: Powertrain: engine and transmission
2: Generic code: same on every make
0: Subsystem depends on the code range
FC: Specific fault in that system

Frequently asked questions

Can I keep driving with code P20FC?

Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

What causes code P20FC?

The most common causes are: chafed wire shorting the pump B control line to ground; water ingress or corrosion in the pump connectors; pump B motor drawing excessive current (internal short or tight motor).

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.