Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Exhaust Air Supply Tube

Symptoms of a Bad or Failing Exhaust Air Supply Tube

The exhaust air supply tube is an exhaust and emissions component that is commonly found on many road going vehicles. Its primary purpose is to allow air into the exhaust stream so that the exhaust gas temperature may rise to the correct level for the catalytic converter to operate. Catalytic converters and oxygen sensors require a specific temperature in order to operate, and are mostly inoperable for the first few minutes after the engine has been started.

The exhaust air supply tube injects air into the exhaust stream right as it exits the engine in order to increase the temperature so that the catalytic converters and oxygen sensors can reach operating temperature as soon as possible. As the exhaust air supply tube is a component of the exhaust system, is it subject to high heat and stress and is therefore susceptible to rust or corrosion due to extreme conditions. When it fails or has any issues, it can cause problems with the drivability and emissions levels of a vehicle. Usually a bad or failing exhaust air supply tube will produce a few symptoms that can alert the driver of a potential issue.

1. Exhaust leaks

One of the first symptoms of a problem with the exhaust air supply tube is an exhaust leak. If the exhaust air supply tube breaks, cracks, an exhaust leak could develop. Exhaust leaks often produce a hissing or tapping sound coming from the engine bay, and if left unchecked can develop into problems with the engine.

2. Engine performance issues

Another symptom of a possible problem with the exhaust air supply tube is engine performance issues. If the tube does indeed develop an exhaust leak, and the leak is large enough, it may cause the vehicle to experience a reduction in power, acceleration, and even fuel efficiency.

3. Increased emissions

Another symptom of a bad or failing exhaust air supply tube is increased emissions. A blocked, clogged, damaged, or broken tube can also cause the vehicle to produce increased emissions. An exhaust leak due to a broken tube can cause the oxygen sensors to give an incorrect reading and decrease the efficiency of the catalytic converter. A clogged tube will restrict the flow of air into the exhaust stream, which will also affect the operation of the oxygen sensors and catalytic converter. Both of these issues can lead to increased emissions output from the engine, which will be an issue for states where emissions are strictly regulated.

While many newer vehicles are now adopting different emissions technologies, and therefore components, exhaust air supply tubes are still commonly found on many road going cars and trucks. If you suspect that your exhaust air supply tube may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if your vehicle is in need of a replacement exhaust air supply tube.

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

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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.


Post a question and get free advice from our certified mechanics.


More related articles

Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...

Related questions

Q: What does the malfunction indicator Warning Light mean?

The malfunction indicator Warning Light is on your instrument cluster. It illuminates when the On-Board Diagnostics-Second Generation (OBD II) system detects an issue. The OBD II system monitors your vehicle’s emissions. When the malfunction indicator Warning Light is illuminated, it...

Q: Catalytic converter bad.

Catalytic converters do have a federal required warranty that most people are unaware of, talk to your dealer to find out if you are still covered. Early catalytic converter failure can be cause by other factors including coolant contamination can...

Q: Ticking on cold starts. Lasts 1-5 minutes.

This is a common issue with the Ford F-150 trucks and is often times related to an exhaust manifold leak. Try starting the truck and smelling underneath the hood for a strong exhaust smell on either side of the engine....