What P0419 means
After a cold start the secondary air (AIR) pump blows fresh air behind the exhaust valves so that unburnt fuel burns off and the catalyst heats up faster; a shut-off valve opens the path and stops exhaust from flowing back.
How the engine computer detects it
Control B is the drive circuit of a second pump or pump relay, found only on systems with two pumps or relays, for example large V engines with one pump per bank. It is checked like P0418 by comparing the driver's feedback with its commanded state. No manufacturer document available to us describes P0419 specifically; Pierburg's fault table lists it as relay B with the same remedies as relay A.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Second pump does not run
- Secondary air readiness not set (emission test)
- Driving normal
Common causes
- Pump relay B faulty Most likely
- Wire or connector to relay B faulty Most likely
- Fuse or supply Possible
- Pump B blocked (consequential damage) Less likely
- Engine module Less likely
How to diagnose P0419
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: air pump relay b, secondary air pump, relay wiring, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 4
- Auxiliary emission controls
- 19
- Specific fault
Questions drivers ask
Can I drive with code P0419?
Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.
Will my car pass an emissions inspection with P0419?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0419 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0419 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.