Just failed the CA smog test on my 94 xjs 4.0. Mechanic said it is because of too much fuel. HC(PPM) and CO% failed.

I am also getting a code FF17 that points to a bad TPS. Just wondering if the TPS going bad can have anything to do with the fuel/ air mixture.

I ordered a new o2 sensor since it was only $30 and the car has 110k on it. My xjs just has one sensor. It attaches right after the y connection... I'm yet to see a direct replacement for this type.

Anyone else here struggle with the CA smog on their xjs? I believe the front two cats are the originals. Hoping not having to replace those.

 

Yes, a TPS code will probably cause a failed emission test. Any time the Check Eng light is on the system IS NOT actually in full control of fueling. With the light on it is in some form of default and is ignoring the O2 sensor. Those defaults rely heavily on the TPS, if yours has a fault the problem is most likely compounded.

Cheers,