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 looseness, corrosion, or heat damage
- 3
Basic tool needed
Check whether the code appeared after wet weather or recent exhaust work
- 4
Basic tool needed
If the system uses vacuum control, inspect the hose routing and solenoid operation too
- 5
Basic tool needed
If scan data is available, compare commanded valve operation with actual response
If the code returns
- -If the valve does not respond, the valve or control side 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 connector fit and control side again.
Background
What this code means
P0415 is a generic OBD-II code for a secondary air injection switch valve B circuit malfunction.
That usually means the second valve or control branch in the secondary air system is not responding the way the ECU expects.
Diagnosis
Common causes
Failed switch valve B
The valve may no longer open or close reliably.
Connector or wiring issue
A poor connection can interrupt the valve circuit.
Vacuum supply problem
The valve may not be getting the pressure it needs.
Moisture or corrosion
Water intrusion can damage the valve or connector.
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
P0410
P0410 usually means the secondary air injection system is not working properly.
P0411
P0411 usually means the secondary air injection flow is incorrect.
P0412
P0412 usually means the secondary air injection control circuit has a malfunction.
P0413
P0413 usually means the secondary air injection valve circuit is malfunctioning.
P0414
P0414 usually means the secondary air injection switch valve A is shorted or malfunctioning.
Source notes
Generic OBD-II (SAE J1979 / ISO 15031-5). P0415 was expanded around common secondary-air switch-valve B faults, including valve failure, wiring damage, and vacuum supply problems.
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