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Getting ready to take a big trip and when I ran a KOER test I got a code 311 thermactor air system fault. Having some trouble understanding forums online so what causes code 311? I have no CEL and truck has runs fine so I'm kind of surprised there's a code. Should I be concerned about 6 hours of driving?
Hey I'm listening. I didn't think I got it mixed up but ain't impossible so I'd appreciate your thoughts.
Code 311: AIR system not working - single, right, or rear HO2S, do you have one after the cat? It could be sensing air not properly diverted, check your vacuum lines to the solenoids.
Code 311: AIR system not working - single, right, or rear HO2S, do you have one after the cat? It could be sensing air not properly diverted, check your vacuum lines to the solenoids.
(All Mixed Up is a song by the band 311)
No just a single O2 sensor before cat. That's where I'll start. Thanks for the help!
Since your truck is a '94, you'll have this combination valve at the back of the engine, instead of separate TAD and TAB valves, that are shown in the video, but the system works the same way. The green hose is coming from the air pump. The blue hose is coming from the crossover pipe, that runs between the heads. The hose marked CAT, goes to the catalytic converter.
The default position of these valves is to either direct the air pump air out of the system, or to direct the air pump air to the catalytic converter, so I wouldn't worry about driving the truck with the system not functioning.
During the key on engine running test, the ECM sends air to the back of the heads, and watches the O2 sensor, to monitor the change. If one of the valves isn't functioning correctly, you get the code 311.
TAD is Thermactor Air Divert (to the heads, upstream of the O2 sensor; or to the catalytic converter, downstream of the O2 sensor), TAB is Thermactor Air Bypass (out of the system).
Here's a video on how the air injection system works. https://youtu.be/qVw3mf_yEgM?si=ii72SKEOOBkdWnDQ
Since your truck is a '94, you'll have this combination valve at the back of the engine, instead of separate TAD and TAB valves, that are shown in the video, but the system works the same way. The green hose is coming from the air pump. The blue hose is coming from the crossover pipe, that runs between the heads. The hose marked CAT, goes to the catalytic converter.
The default position of these valves is to either direct the air pump air out of the system, or to direct the air pump air to the catalytic converter, so I wouldn't worry about driving the truck with the system not functioning.
During the key on engine running test, the ECM sends air to the back of the heads, and watches the O2 sensor, to monitor the change. If one of the valves isn't functioning correctly, you get the code 311.
TAD is Thermactor Air Divert (to the heads, upstream of the O2 sensor; or to the catalytic converter, downstream of the O2 sensor), TAB is Thermactor Air Bypass (out of the system).
Thanks! Starting to make a little more sense now lol.
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