P1231 Code: Meaning, Symptoms, Causes & Fix

Overview

Code P1231 indicates a fault in Fuel Pump Secondary Circuit Low, High Speed, typically within fuel delivery and pressure control.

Symptoms

hesitation under acceleration
reduced fuel economy
hard starting

Common causes

Disconnected or loose connector affecting fuel pump secondary circuit low, high speed
Open circuit in wiring
Connector pin damage/corrosion or harness stress near related components

How to diagnose P1231

Confirm P1231 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to fuel pump secondary circuit low, high speed for obvious defects.
Use a continuity test from module pin to component to identify opens/high resistance.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P1231

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with P1231?

Most vehicles can be driven short-term with P1231, but postpone heavy load/highway driving until repaired.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (open) in the fuel pump secondary circuit low, high speed circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify P1231 remains cleared under the conditions that originally set the code.

Fix options

Repair open circuit and secure connector lock.
Restore continuity and verify pin tension.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$220-$1100

Common mistakes when diagnosing P1231

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

P1231 in common vehicles

P1231 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P1231?

P1231 is commonly set by open faults affecting fuel pump secondary circuit low, high speed.

How much does it cost to fix P1231?

For P1231, repair costs are typically $220-$1100 depending on exact root cause, labor rates, and part quality.

Can I clear P1231 without repair?

You can clear P1231 temporarily, but the code usually returns until the underlying fault is corrected.