Can you keep driving?
Can you keep driving?
Stop driving if any of these apply
- !The engine starts running much worse, stalls, or the warning light flashes.
- !The vehicle begins to overheat, knock, or lose power sharply while the code is active.
What to check first
Step-by-step checks
- 1
Free - no tools
Let the exhaust cool before checking the valve and wiring
- 2
Free - no tools
Inspect the valve connector and harness for heat damage, corrosion, or looseness
- 3
Basic tool needed
Check whether the code appeared after wet weather, a cold start, or recent exhaust work
- 4
Basic tool needed
If scan data is available, compare commanded valve operation with actual response
- 5
Basic tool needed
If the pump runs but the valve does not open, focus on the valve circuit and plumbing
If the code returns
- -If the valve does not respond to command, the actuator or wiring becomes more likely.
- -If the harness movement changes the fault, wiring repair comes before a new valve.
- -If the code returns after replacement, recheck the control side and connector fit.
Background
What this code means
P0413 is a generic OBD-II code for a secondary air injection valve circuit malfunction.
That usually means the ECU cannot control the valve correctly, so air does not reach the exhaust the way it should during cold start.
Diagnosis
Common causes
Failed secondary air valve
The valve may no longer open or close reliably.
Wiring or connector issue
A poor connection can prevent valve operation.
Moisture or corrosion
Water intrusion can damage the valve circuit or connector.
Relay or supply fault
The valve may not be getting power or command correctly.
Avoid these mistakes
What not to do
- xDo not replace the sensor or valve first if there is obvious wiring, connector, or vacuum damage.
- xDo not ignore drivability changes just because the code sounds like an emissions fault.
Parts
Parts that may need replacing
See also
Related OBD codes
Source notes
Generic OBD-II (SAE J1979 / ISO 15031-5). P0413 was expanded around common secondary-air valve circuit faults, especially valve failure, connector damage, and moisture-related issues.
This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.
This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.
Last reviewed: 2026-04-10
Reference: Open reference