P027D: Fuel Pump Module B Control Circuit High

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. P027D means the control circuit to pump module B reads high, typically a short to voltage – the counterpart of P025D. Ford lists it in the low-pressure lift pump monitor of its 2023 diesels, monitored continuously and set within 0.5 s, without its own threshold. Pump B may then run all the time or not at all.

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
Pump B runs all the time or not at all
Starting problems

Most likely causes

Control line to module B shorted to voltage
Moisture or corrosion in the connector
Pump control module B faulty

What to check, in order

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

Check the pump's fuse, relay, and connector
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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 P027D means

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

Frequently asked questions

Can I keep driving with code P027D?

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

What causes code P027D?

The most common causes are: control line to module B shorted to voltage; moisture or corrosion in the connector; 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.