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 relay and wiring
- 2
Free - no tools
Inspect the relay, fuse, and socket for heat damage, corrosion, or looseness
- 3
Basic tool needed
Listen for the pump at cold start if the vehicle normally runs it briefly
- 4
Basic tool needed
Check whether the code appeared after wet weather or recent electrical work
- 5
Basic tool needed
If scan data is available, compare commanded relay operation with actual pump response
If the code returns
- -If the relay does not switch properly, it rises to the top of the list.
- -If the pump works directly but not through the relay branch, the control side is more likely.
- -If the code returns after a repair, recheck the socket and feed path before buying more parts.
Background
What this code means
P0419 is a generic OBD-II code for a secondary air pump relay B circuit malfunction.
That usually means the second relay or relay branch in the system is not switching the way the ECU expects during cold-start operation.
Diagnosis
Common causes
Failed relay
The relay may not switch reliably when commanded.
Socket or connector damage
Heat or corrosion can keep the relay from making contact.
Wiring issue
A damaged harness can interrupt the relay branch.
Power feed problem
The relay may be healthy but not getting proper supply.
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.
P0415
P0415 usually means the secondary air injection switch valve B has a circuit malfunction.
P0416
P0416 usually means the secondary air system switch valve B is malfunctioning.
P0418
P0418 usually means the secondary air pump relay A circuit has a malfunction.
Source notes
Generic OBD-II (SAE J1979 / ISO 15031-5). P0419 was expanded around common secondary-air pump relay B faults, especially relay failure, socket damage, and wiring 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