Limp-in mode?

[phiebert]

When the PCM has entered a Limp-in mode (identified a failed emission component) what exactly does it do? Does it change the A/F ratio?

I have something wrong with my air temp sensor that I am trying to figure out. I get a code 23 and my check engine light comes on and stays on once in awhile (until I shut the engine off). I read that if the light is on the engine is in Limp-in mode. Just wondering what that means because it doesn't appear to run any differently.

 

[Nadine UK GTS]

For a '97:

Code 23 is "intake air temp sensor voltage low / high"

Basicly the voltage to that sensor is below or above the acceptable voltage. Yes, your check engine light will be illuminated during engine operation. But I don't think you will go into limp in mode (when MIL is on all the time).

 

[GTS Dean]

Did you start the engine with the IAT sensor unplugged? This will trip a fault code and illuminate the MIL. Sometimes, the light will clear after several key-on, key-off cycles, but the code will still be in memory.

When one of your sensors dies, the computer begins to take readings from others and interpolate a surrogate value based on long-term adaptive fuel strategy block values stored in the PCM.

 

[Motor City Mad Man]

I hear a ground up ****** tablet in the gas tank works good to combat the limp-in mode. Should also add about 50 hp.

 

[Viper Wizard]

No Sean it's two tablets per mile of limp -in!

Patrick, I just faxed you the codes, but you need to order the diagnostic books!!

 

[phiebert]

Thanks Chuck and Marv for your help!

Sean, I've added two tablets but still no luck, maybe I need new rubber??