What does it mean?
This diagnostic code (DTC) is a generic powertrain code, meaning it applies to vehicles equipped with OBD-II (Dodge, Ram, Ford, GMC, Chevrolet, VW, Toyota, etc.). Although generic, specific repair steps may vary by make/model.
When diagnosing a P0413 code, it means the Powertrain Control Module (PCM) has detected a malfunction in a switching valve circuit of the Secondary Air Injection (SAI) system. This particular switching valve is designated as A. The A designates a specific switching valve in a system that uses multiple switching valves, or the only valve if there is only one switching valve.
In diagnostic terms, the word “open” could be substituted for disconnected, broken, or severed. Consult a reliable vehicle information source to determine the SAI switching valve circuit configuration for the vehicle in question and the exact location of switching valve A. To reduce harmful exhaust emissions, the SAI system pumps ambient air into the engine’s exhaust system. Most automotive SAI systems use a belt-driven pump to draw in ambient air, slightly compress it, and inject the pressurized air into the engine’s exhaust manifolds.
One-way valves, switching valves, check valves, and bypass valves, controlled by the PCM, are used to regulate and distribute air pressure as well as protect the SAI pump. The PCM receives voltage input signals from strategically placed pressure sensors to monitor SAI system pressure fluctuations. When the required parameters are met, the PCM electronically opens the necessary valves and allows secondary air to be pumped into the exhaust system.
Some vehicles are equipped with SAI systems designed with an electric pump. In this type of system, the PCM monitors pressure sensors and activates the pump if necessary.
If the PCM detects a voltage input signal from the SAI switching valve (designated A) that is too low or non-existent, a P0413 code will be stored and a malfunction indicator light may be illuminated.
Other secondary air injection system fault codes include P0410, P0411, P0412, P0414, P0415, P0416, P0417, P0418, P0419, P041F, P044F, P0491, and P0492.
Code Severity and Symptoms
The SAI system is only related to reducing exhaust emissions and is not essential to engine operation. A stored P0413 code should not be considered severe.
Symptoms of this code may include:
- There are probably no symptoms associated with this code
- A hissing or choking noise from the pipes or SAI pump is possible
- Loud whining from the SAI pump
Causes
Possible causes for this code being set are:
- Burned or broken wiring and/or connectors in the SAI system
- Frozen SAI pump (in extremely cold climate geographical areas)
- Faulty SAI pump
- Faulty SAI pump relay
- Bad SAI pressure sensor
Diagnostic and Repair Procedures
A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information will be needed to diagnose a P0413 code.
I would begin my diagnosis by inspecting the system’s wiring and connectors and the serpentine belt that drives the pump (if applicable). Repair or replace open circuits as needed and retest the system. If the pump is belt-driven and the belt is missing or otherwise defective, replace it before continuing. Ensure the pump spins freely by hand before replacing the belt. Pump failure is relatively common in high-mileage vehicles. If the SAI pump is driven by an electric motor, I also like to check the system fuses and relays at this point.
If a visual inspection does not lead to any obvious malfunction, connect the scanner to the vehicle’s diagnostic port and retrieve all stored codes and freeze frame data. This information can be useful in my diagnosis, so I like to write it down. Now, clear the codes and test-drive the vehicle to see if the P0413 resets.
Consult your vehicle information source to search Technical Service Bulletins (TSBs) for entries matching the code(s) and symptom(s) presented by the vehicle in question. Since TSBs are compiled using data from hundreds of thousands of repairs, the information they contain can be very helpful in reaching a successful diagnosis.
In extremely cold weather conditions, belt-driven SAI pumps are prone to seizing due to frozen condensation. Typically, a one-way check valve is built into the air supply pipe to prevent condensation from reaching the SAI pump. One-way check valves regularly fail and allow exhaust condensation to enter the SAI pump. Once the condensation freezes, the ice seizes the (belt-driven) SAI pump or causes it to bind and blow a fuse (electric pump).
Use the scanner to activate the electric SAI pump. Once the pump is activated, use the DVOM to test for voltage and ground at the SAI pump. If no voltage is detected, suspect a blown fuse or a faulty power relay. If all fuses and relays are good, use the DVOM to check for an open circuit between the power source and the pump. Disconnect all associated controllers before using the DVOM to check circuit resistance. If no ground is detected, use your vehicle information source to locate the proper ground source and test for voltage drop in the circuit.
Test the SAI pressure sensor using the DVOM and the specifications located in your chosen vehicle information source.
Additional diagnostic notes:
- Blown fuses are usually a reaction to a short circuit and not the source of the malfunction
- Frozen pumps may be thawed before use to avoid catastrophic damage to the pump