Error code

OBD2 P0231

OBD2P0231
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Fuel Pump Secondary Circuit Low.

Severity

highThe vehicle may be drivable but should not be driven for extended periods as it poses a safety risk.

Summary

P0231 indicates low voltage in the secondary circuit of the fuel pump relay, which can prevent proper fuel delivery to the engine.

Symptoms

  • Engine may not start or stall shortly after starting
  • Check Engine Light (CEL) illuminates

Common Causes

  • Faulty fuel pump relay
  • Harness damage causing excessive resistance, open circuit, intermittent open circuit, or short to ground
  • Feedback circuit issues leading to incorrect signal to ECM
  • Activated inertia switch interrupting fuel pump power flow

Diagnosis

  1. Check battery voltage (12.6V off, 13.5V running)
  2. Inspect fuel pump fuse
  3. Test relay and circuit resistance with multimeter
  4. Verify continuity between relay secondary circuit and ECM

Fixes

  • Replace faulty fuel pump relay or repair damaged wiring

FAQ

What should I do if the P0231 code appears?

First, check your battery voltage and fuel pump fuse. If these are fine, proceed to test the relay and circuit resistance using a multimeter.

Can I drive with this code active?

It is not recommended to drive for extended periods as it may indicate issues that could lead to engine stalling or other drivability problems.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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