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P2257 OBD-II Trouble Code: Secondary Air Injection System Control A Circuit Low

Check Engine Light

P2257 code definition

Secondary Air Injection System Control A Circuit Low

What the P2257 code means

P2257 is an OBD-II generic code. The Engine Control Module (ECM) monitors the secondary air injection system control valve A circuit, when the system is not activated and detected the circuit return voltage to be low. The ECM then activates the Check Engine Light and stores the P2257 code.

What causes the P2257 code?

  • The air injection control valve A has an open or short circuit.

  • A broken wire or connector for the control valve A at the valve connection.

  • An open wire on the power supply circuit from the ECM to control valve A.

  • An open or short on the return signal control wire back to the ECM from the control valve.

  • The ECM has an internal fault or defect.

What are the symptoms of the P2257 code?

  • The Check Engine Light will be illuminated and the code P2257 is set in ECM memory as a fault.

  • The ECM cannot control the secondary air injection valve A.

  • The ECM may go into failure management mode causing the engine to have reduced power.

How does a mechanic diagnose the P2257 code?

  • Scan codes and document the codes in the ECM and look at the freeze frame data for failure.

  • Measure the voltage to and from the air injection control valve A and check it per specifications.

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

  • Check the harness for short or broken wires.

  • Follow the manufacturer pinpoint testing if the problem is not found.

Common mistakes when diagnosing the P2257 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 replacing any parts in the system.

How serious is the P2257 code?

Code P2257 is for the air injection system for the emission control of the engine. The injected air controls excessive fuel in the exhaust could leave the engine to burn off the excessive fuel, therefore causing the exhaust emission levels to stay below allowed levels. The vehicle fails emissions if this system is not working properly.

What repairs can fix the P2257 code?

  • Replacing the air injection control valve A for a short or open internal circuit.
  • Repair an open or short in the sensor wiring or connector to the air injection control valve.
  • Replace the ECM for an internal failure.

Additional comments for consideration regarding the P2257 code

Code P2257 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 one way check valve, which allows hot exhaust to get to the the control valve and melt it causing this failure to happen. Check the one way check valve if the injection control valve show any signs of melting and replace both components.

Need help with a P2257 code?

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