Symptoms of a Bad or Failing Air Pump Check Valve

The secondary air injection system is an emissions system equipped on many road going vehicles. It is composed of several components that work together to reduce the vehicle’s tailpipe emissions. One of these components is the air pump check valve. The air pump check valve is the valve that allows air supplied from the air pump to be pumped into the exhaust stream to reduce hydrocarbon and carbon monoxide tailpipe emissions. It functions as a one-way valve, allowing the air to pump through into the exhaust, while preventing the exhaust fumes from leaking into the secondary air injection system.

When the air pump check valve fails, it can lead to a variety of problems, notably a significant increase in the vehicle’s tailpipe emissions. Usually, when the air pump check valve fails, it will display a few symptoms that may alert the driver of a potential problem that should be inspected.

1. Exhaust fume odor

One of the first and most common symptoms of a bad or failing check valve is an exhaust fume odor. The odor is a result of exhaust leaking either from the valve housing, or through the actual check valve back into the secondary air injection system. The odor may become most noticeable at idle speeds. Any sort of odor indicates an exhaust leak, which compromises emissions.

2. Failed emissions test

Many states require their road-going vehicles to pass an emissions test in order for the vehicle to be legally operated. If the air pump check valve fails, it can significantly impact the tailpipe emissions of a vehicle. The air pump check valve works to reduce hydrocarbon and carbon monoxide emissions of a vehicle, so when it fails, the levels of these two pollutants will increase.

3. Check Engine Light is On

Another common symptom of a failed air pump check valve is the Check Engine Light coming on. When a problem is detected by the vehicle’s computer, it will set off a code and activate the Check Engine Light. Having the vehicle scanned for trouble codes can reveal if there may be a problem with the air pump check valve that needs to be addressed.

As the air pump check valve is part of the vehicle’s emissions system, is it is very important that it functions correctly so that the vehicle can remain at acceptable emission levels. If you suspect that your air pump check valve may be having a problem, or your Check Engine Light has come on, have the vehicle diagnosed by a professional technician, such as one from YourMechanic. They will be able to determine if the vehicle needs an air pump check valve replacement, or if another repair needs to be made.


Next Step

Schedule Vehicle Engine Mechanical Inspection

The most popular service booked by readers of this article is Vehicle Engine Mechanical Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Vehicle Engine Mechanical Inspection reviews

Excellent Rating

(171,627)

Rating Summary
161,099
5,644
1,174
834
2,876
161,099
5,644
1,174
834
2,876

Rusty

23 years of experience
512 reviews
Rusty
23 years of experience
GMC Sonoma L4-2.2L - Vehicle Engine Mechanical Inspection - Arlington, Texas
Great overall impressions. Vechile is driveable and runs terrific now.

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Cadillac Brougham V8-5.7L - Vehicle Engine Mechanical - Las Vegas, Nevada
Talent and passion for what you do in any field is critical, Raymond seems to have both. I have dealt with many Mechanics in my day Raymond is one of the best. Thank you sir.

Willie

24 years of experience
114 reviews
Willie
24 years of experience
Saturn Vue L4-2.4L - Transmission Fluid Service - Long Beach, California
Good work, friendly

Jay

37 years of experience
947 reviews
Jay
37 years of experience
Nissan Altima L4-2.5L - Engine or Transmission Mount Replacement - Riverside, California
Quality mechanic.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace an Air Pump Check Valve
The air pump check valve allows air into the exhaust system. It also prevents exhaust gases from reentering the system during a backfire or failure.
How to Change a Radiator Valve
A radiator valve allows coolant into the radiator in order to cool off the engine once the coolant has reached a certain temperature.
How to Replace a Positive Crankcase Ventilation (PCV) Valve
A positive crankcase ventilation valve improves emissions in modern engines. Signs of PCV valve failure include oil leaks and poor engine performance.

Related questions

When I put it in reverse it is stalling
If you car only stalls when you shift into reverse and not when you shift to any forward drive gear, then you may have an internal leak in the valve body and when you shift into reverse, the transmission is...
Car shuts off when put in to gear after turning on
Your car seems to be showing symptoms similar to a vehicle with a dirty or failing idle air control valve (https://www.yourmechanic.com/services/idle-control-valve-replacement). This valve regulates airflow when the throttle plate is closed, and if clogged, you will have to usually keep...
A.I.R. pump is missing in my car
Hello. The A.I.R. system is an emissions system that is designed to inject air into the exhaust manifold to help with the combustion of any unburned fuel before it reaches the catalytic converter, resulting in cleaner emissions. In order to...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com