What does P1231 mean on a Ford?

P1231. High Speed Fuel Pump Relay Activated. Applies to F-150, Explorer, Ranger, Taurus with two-speed fuel pumps.

What causes P1231 on a Ford?

PCM commanding high speed to compensate for low fuel pressure Weak fuel pump unable to hold pressure on low speed Clogged fuel filter raising pump workload Failing high-speed relay sticking on Fuel pressure sensor misreporting low pressure

How do I fix P1231 on a Ford?

Replace the fuel filter and re-test before deeper diagnosis Read actual fuel pressure against desired on a scanner Test the high-speed relay for sticking contacts Verify pressure sensor accuracy with a mechanical gauge Replace the pump if it cannot hold pressure on low speed

Code

P1231

High Speed Fuel Pump Relay Activated

Category: Powertrain - Fuel/Air Metering
Severity: Check Engine Light
Applies to: F-150, Explorer, Ranger, Taurus with two-speed fuel pumps
Related: P0230 Fuel Pump Primary Circuit on OBD Codes List

Findings, check these first

PCM commanding high speed to compensate for low fuel pressure
Weak fuel pump unable to hold pressure on low speed
Clogged fuel filter raising pump workload
Failing high-speed relay sticking on
Fuel pressure sensor misreporting low pressure

Standard procedure

Replace the fuel filter and re-test before deeper diagnosis
Read actual fuel pressure against desired on a scanner
Test the high-speed relay for sticking contacts
Verify pressure sensor accuracy with a mechanical gauge
Replace the pump if it cannot hold pressure on low speed

Code lookup

Type a code above, or start from a symptom or a common code.

Press / to jump to the box. Ford-enhanced powertrain, body, chassis and network codes. Generic P0xxx codes live on OBD Codes List.

Sources and review

Review: checked against the recorded source material.

OBDII.pro: P1231 Ford definition
live reference page (obdii.pro)
Supports: Ford-family meaning for P1231: Fuel Pump Secondary Circuit Low, High Speed
Fetched directly. obdii.pro is a publisher independent of the engine-codes family.
P1231 FORD Code: Meaning, Causes, and Symptoms | OBD2 Codes
live reference page (obd2-codes.co)
Supports: Ford meaning for P1231: High Speed Fuel Pump Relay Activated
Fetched directly. obd2-codes.co phrasing matches the engine-codes family, so it counts as one publisher.

Last updated 2026-09-04.

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