P027C: Fuel Pump Module B Control Circuit Low

On demand-controlled fuel systems the engine module does not drive the pump itself but sends a pump control module the desired pump output on a separate control line, usually as a duty cycle; the module reports back on a monitor line or via CAN. Module B is a second pump module, for example on dual-tank commercial vehicles. P027C means the control circuit to pump module B reads low, typically a short to ground – the counterpart of P025C. Ford lists it in the low-pressure lift pump monitor of its 2023 diesels, monitored continuously and set within 0.5 s, without stating its own threshold or which vehicle has a module B.

Medium severity. Can I keep driving?Avoid long trips and hard acceleration. If you smell fuel or the car stalls, do not continue.

Symptoms

Check engine light on
Starting problems or stalling
Loss of power from low supply pressure

Most likely causes

Control line to module B shorted to ground
Connector at module B corroded or wet
Pump control module B faulty
Ground point

What to check, in order

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

Check the pump's fuse, relay, and connector
With the connector unplugged, check whether the signal wire is making contact with ground.
Replace the filter if it is due for maintenance
Compare commanded and actual pressure in live data
Measure the pressure with a suitable gauge
Check the sensor and regulator before replacing the pump

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P027C means

P: Powertrain: engine and transmission
0: Generic code: same on every make
2: Fuel injection
7C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P027C?

Avoid long trips and hard acceleration. If you smell fuel or the car stalls, do not continue.

What causes code P027C?

The most common causes are: control line to module B shorted to ground; connector at module B corroded or wet; pump control module B faulty.

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.