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P0416 is a diagnostic trouble code (DTC) for "Secondary Air Injection System Switching Valve B Circuit Open". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The powertrain control module (PCM) has detected a problem in the secondary air injection system, which reduces emissions by pumping ambient air into the exhaust stream.
The PCM reads the condition of the secondary air injection system in increments of pressure and flow, which translate to input voltage from sensors. If input readings fluctuate by more than ten percent, a code will be stored and the malfunction indicator lamp (MIL) will illuminate. Some models require multiple drive cycles for the MIL to illuminate, but the code will usually be stored on the initial incident.
Usually driven by the serpentine belt, the secondary air injection system uses a pump often called the “smog pump” to inject ambient air into the exhaust stream, reducing emissions. Heat-resistant silicon hoses direct cooler ambient air to the pump, while filtered air comes in through the air filter housing. This cooler air is directed into the exhaust system with silicon and steel lines, with a one-way check valve fitted on each exhaust hose to prevent condensation from backing up into the pump and causing problems. These valves are prone to failure.
Engines that use a V configuration usually feature dual inlet ports in the exhaust pipes and dual one-way check valves from the pump.
Replacing the secondary air injection pump without devising a water drain on the pump housing can lead to repeated failures of the pump. It’s also essential to test one-way check valves for a proper diagnosis.
A P0416 code can lead to an illuminated MIL and a failed emissions test.
More often than not, the check valves or the secondary air injection system pump are at fault. Failed check valves can introduce water back into the pump, and in cold weather this can cause the pump to seize or cause other types of catastrophic failure. Diagnosis should start with inspection of the pump and check valves. Other emissions-related codes may accompany a P0416 code, but it’s important to start with these components first.
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