Technical Description of OBD-II Trouble Code
Short Circuit in Circuit A of Secondary Air Injection System Switching Valve
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code, which means it is applicable to OBD-II equipped vehicles (Dodge, Ram, Ford, GMC, Chevrolet, VW, Toyota, etc.). Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
A stored code P0414 indicates that the powertrain control module (PCM) has detected a short in the circuit of a secondary air injection (SAI) system switching valve. This particular switching valve is designated as A and refers to a specific valve in a system that uses multiple switching valves, or the only valve if it is a single valve system. A shorted circuit could occur if the affected circuit comes into contact with an unexpected voltage signal or a ground. A shorted circuit typically results in a blown fuse.
The SAI system injects ambient air into the engine exhaust system to reduce harmful exhaust emissions. Automotive SAI systems use either a belt-driven pump or an electric pump to draw in ambient air, slightly compress it, and inject the pressurized air into the engine exhaust manifolds. One-way valves, switching valves, anti-backfire valves, and bypass valves (controlled by the PCM) are used to regulate and distribute air pressure and protect the SAI air pump.
The PCM receives voltage input signals from pressure sensors to monitor fluctuations in SAI system pressure. When the appropriate conditions are met, the PCM electronically opens the necessary valves and allows secondary air to be pumped into the exhaust system. The PCM monitors SAI pressure sensors and activates the pump when required in vehicles equipped with electric pumps.
If the PCM detects a voltage input signal from the SAI switching valve (designated as A) circuit that indicates a short (to voltage or ground), a code P0414 will be stored and a malfunction indicator lamp may illuminate.
Other trouble codes related to the secondary air injection system include P0410, P0411, P0412, P0413, P0415, P0416, P0417, P0418, P0419, P041F, P044F, P0491, and P0492.
Code Severity & Symptoms
A stored code P0414 is not considered severe. The SAI system is only related to reducing exhaust emissions and is not essential for engine operation. However, if the SAI circuit is shorted to voltage, constant activation of the motor could lead to a discharged battery.
Symptoms of this code may include:
Causes
Possible causes for this code to be set are:
Diagnostic and Repair Procedures
To correctly diagnose a code P0414, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information (such as All Data DIY).
Start your diagnosis by inspecting the system wiring, connectors, and the serpentine belt that drives the pump (if applicable). Repair or replace any shorted circuits as necessary and retest the system. If the belt is missing or defective (for belt-driven pumps), replace it before proceeding. Make sure the pump turns freely by hand before replacing the belt. If the SAI pump is driven by an electric motor, I recommend checking system fuses and relays at this time.
Next, connect the scanner to the vehicle diagnostic port and retrieve all stored codes and freeze frame data if your visual inspection does not reveal any obvious malfunctions. It is helpful to write down this information as it may be useful later in the diagnosis. Clear the codes and test-drive the vehicle to see if the P0414 code is reset.
Use your vehicle information source to search for technical service bulletins (TSBs) that match the code/s and symptoms exhibited by the vehicle in question. TSBs contain a wealth of repair information and can be very helpful in reaching a successful diagnosis. Belt-driven SAI pumps are prone to lockup in extreme cold weather conditions due to frozen condensation. An integrated one-way check valve in the air inlet hose is designed to prevent condensation from reaching the SAI pump. However, these check valves may fail and allow condensation from the exhaust to enter the SAI pump, causing it to freeze and seize (for belt-driven pumps) or bind and blow a fuse (for electric pumps).
Proceed by using the scanner to activate the electric SAI pump. After the pump has been activated, use the DVOM to test voltage and ground at the SAI pump. If no voltage is detected, suspect a blown fuse or a faulty power supply relay. If all fuses and relays are good, use the DVOM to check for an open circuit between the power supply source and the pump. Before checking circuit resistance with the DVOM, disconnect all related controllers.
Use the DVOM and a wiring diagram from your vehicle information source to test individual system circuits for shorts to ground or voltage. Repair or replace circuits that have unexpected ground or voltage signals.
Additional diagnostic notes:
