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.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Exhaust Air Supply Tube and was authored by Ed Ruelas.