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P2259 OBD-II Trouble Code: Secondary Air Injection System Control B Circuit Low

Check Engine Light

P2259 code definition

Secondary Air Injection System Control B Circuit Low

What the P2259 code means

P2259 is an OBD-II generic code. The engine control module (ECM) monitors the secondary air injection system control valve circuit when the system is not activated and detects the circuit return voltage to be low. The ECM then activates the Check Engine Light and stores the P2259 code.

What causes the P2259 code?

  • The air injection control valve has an open or short circuit.
  • A broken wire or connector for the control valve at the valve connection
  • An open wire on the power supply circuit from the ECM to the control valve
  • An open or short on the return signal control wire back to the ECM
  • The ECM has an internal fault.

What are the symptoms of the P2259 code?

  • The Check Engine Light will be illuminated and the code P2259 is set in ECM memory as a fault.
  • The ECM cannot control the secondary air injection valve.
  • The ECM may go into failure management mode causing the engine to have reduced power.

How does a mechanic diagnose the P2259 code?

  • Scans codes and documents the code in the ECM and look at the freeze frame data for failure.

  • Measures the voltage to and from the air injection control valve as per specifications.

  • Measures the resistance of the control valve circuit at the ECM and at the valve and check to specifications.

  • Checks the harness for short or broken wires.

  • Follows manufacturer pinpoint testing if problem is not found.

Common mistakes when diagnosing the P2259 code?

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired.

  • Failing to clear the ECM codes after the codes are fixed

  • Failing to verify the fault before testing the system codes

How serious is the P2259 code?

Code P2259 is for the air injection system for emission control of the engine. The injected air controls excessive fuel in the exhaust leaving the engine to burn off the excessive fuel so the exhaust emission levels stay below allowed levels. The vehicle fails emissions if this system is not working properly.

What repairs can fix the P2259 code?

  • Replacing the air injection control valve
  • Repairing an open or short in the sensor wiring or connector
  • Replacing the ECM for an internal failure

Additional comments for consideration regarding the P2259 code

Code P2259 may not cause an engine drive complaint on some vehicles but can cause the exhaust to overheat causing catalyst damage and failed emissions. The most common failure is the exhaust check valve allowing hot exhaust to get to the control valve and melt it causing this failure to happen. Check the one-way check valve if the injection control valve shows signs of melting.

Need help with a P2259 code?

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The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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