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P0233 OBD-II Trouble Code: Fuel Pump Secondary Circuit Intermittent

Check Engine Light

P0233 code definition

Fuel pump Secondary Circuit Intermittent

What the P0233 code means

P0233 is a generic OBD-II code that is triggered when the engine control module (ECM) detects that the secondary circuit to the fuel pump has an intermittent voltage when the fuel pump relay is turned on.

What causes the P0233 code?

  • The engine control module (ECM) detects low, or no voltage to the secondary fuel pump circuit when the fuel pump relay is turned on

  • The fuel pump relay may have a poor or intermittent contact internally on the secondary side of the relay

  • The inertia fuel shutoff switch (IFS) is not passing voltage through it intermittently to the pump

What are the symptoms of the P0233 code?

  • The Check Engine Light will be illuminated and the P0233 code set

  • The engine will not start from lack of fuel pump operation whenever the problem is occurring

  • The engine may run normally until the problem occurs, then it will lose power and the engine will stall

How does a mechanic diagnose the P0233 code?

  • Scans codes and documents the freeze frame data in order to verify the problem

  • Clears the DTC codes to verify whether the concern comes back

  • Checks the IFS connection for any loose or corroded pins

  • Checks the fuel pump feed fuse or fusible link to see if it has a good contact to vehicle power

  • Tests to see if voltage is getting to the fuel pump secondary circuit through the IFS and relay while wiggling connections and wiring for intermittent connections

  • Lightly taps on relay and IFS to see if connection is lost to power the secondary fuel pump supply voltage

Common mistakes when diagnosing the P0233 code

Follow these simple guidelines to prevent misdiagnosis:

  • Verify that the battery voltage is not low and connections are good, causing intermittent voltage drops in the electrical system

  • Check the electrical connections at the fuel pump relay and at the IFS for any loose connections on the secondary side

How serious is the P0233 code?

  • The fuel pump secondary circuit powers the fuel pump and can cause a no start or the engine to suddenly stall while driving

  • A low battery voltage can trigger the code if the voltage falls below a specified level

What repairs can fix the P0233 code?

  • Replacing the fuel pump relay if it is making intermittent connection on the secondary side of the relay

  • Replacing the IFS or relay if it shows signs of corrosion inside the connections, and cleaning or replacing the connector of all corrosion

  • Repairing a low battery voltage condition by replacing the battery, or repairing and cleaning the connections

Additional comments for consideration regarding the P0233 code

Code P0233 is triggered when the ECM detects intermittent low voltage in the secondary circuit to the fuel pump through the relay falling below a specified voltage. Some vehicles have an IFS and use a relay, so check both of these on those vehicles.

Need help with a P0233 code?

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