P2438 OBD-II Trouble Code: Secondary Air Injection System Air Flow/Press Sensor Circuit High Bank 2

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P2438 code definition

A P2438 trouble code means that the PCM has detected a problem within the secondary air injection system. Another component that can cause a P2438 code to be stored is a problem with the pressure sensor circuit. Bank 2 refers to the bank of the engine that does not contain the first cylinder.

Some other trouble codes often associated with a P2438 code are: P2430, P2431, P2432, P2433, P2434, P2435, P2436, P2437, P2439, P2440, P2441, P2442, P2443, P2444, P2445, P2446, and P2447.

What the P2438 code means

A P2438 trouble code usually is an indication of a variation in the input voltage reading to the PCM of greater than 10 percent. Sometimes, though, a vehicle has to experience this condition during multiple cycles in order for the Check Engine light to be illuminated, though the code is usually stored on the initial failure.

What causes the P2438 code?

A common cause of a P2438 trouble code is a bad check valve in the air inlet hose of the secondary air injection pump. This code most often happens during cold weather, with the check valve allowing condensation from the exhaust system to enter via the injection pump. This moisture freezes during cold weather, causing the secondary air injection pump to bind up, causing a catastrophic pump failure or an overloaded circuit in the form of a blown fuse. Another cause is electrical wiring and connectors getting burnt up by engine exhaust that is hotter than normal.

What are the symptoms of the P2438 code?

In addition to a stored trouble code and illuminated Check Engine light, symptoms of a P2438 trouble code include:

How does a mechanic diagnose the P2438 code?

To diagnose a P2438 trouble code successfully, a mechanic needs an advanced scanner and a digital volt/ohmmeter. The best way to diagnose a P2438 trouble code includes:

  • Inspecting the air inlet hose check valve. If air flows both ways through the valve, then the check valve is bad and needs replacing.

  • The mechanic should also do a visual scan of all secondary air injection pump wiring, connectors, and components.

  • After repairing or replacing wiring, connectors, and components, the mechanic needs to retest the system to ensure everything is in working order.

  • After clearing the P2438 trouble code, the mechanic should then perform a test drive to check if the trouble code returns.

Common mistakes when diagnosing the P2438 code

Mechanics must check the one-way check valve within the air inlet hose to make sure the problem does not lay there. Otherwise, pump replacement can still result in further pump failure as the check valve allows moisture to build up in the pump, causing a failure when the moisture freezes once again during cold weather.

How serious is the P2438 code?

A P2438 trouble code, if not dealt with before cold weather arrives, can cause the secondary air pump to fail due to moisture freezing with it, causing it to bind up. This, in turn, can cause higher-than-normal engine exhaust emissions.

What repairs can fix the P2438 code?

To fix a P2438 trouble code, the mechanic must follow certain steps, including:

  • Inspecting and replacing any damaged or worn wiring, connectors, or components.

  • In addition to shorts and damage to wiring and connectors, a mechanic needs to inspect all secondary air injection system hoses and fittings for any cracking, breaking, or heat damage from higher than normal engine exhaust heat.

  • Replacing or repairing any damaged hoses or components.

  • A mechanic should also check any fuses associated with the secondary air injection system to make sure that they are not blown. If blown, the mechanic should replace the fuses.

  • Retest the system as needed upon making the necessary repairs or replacing any blown fuses.

  • If for some reason a fuse continues to blow, the mechanic should check the secondary air pump to make sure it is not damaged or failing.

  • If the secondary air pump failure is the cause, it should be repaired or replaced it as necessary.

Additional comments for consideration regarding the P2438 code

A failure to replace a one-way check valve can lead to failure due to contaminants entering any replacement pump. The mechanic can prevent this by replacing any faulty one-way check valves they find.

Need help with a P2438 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

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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