Cherokee goes on road (thumbs up) CEL comes on almost immediately (thumbs down)
 

:cursing: Good afternoon all,

Well, it's been a productive week. Bought my 2000 Cherokee Sport 4.0 for $1200.00. Put in the much needed alternator, belt and battery to get it rolling, got it registered and insured and on Tuesday... almost immediately after turning the last screw on its brand new license plates, the CEL comes on. Here in MA you need to have the codes cleared to have it inspected and the codes P0455 (large leak detected) and P0135 (O2 sensor circuit malfunction) popped! Great!!! I've searched and got a lot of insight into what those might be, and hopefully one of the easier solutions will solve my problem. I've also got a blower motor problem. It just "No Worky!" I've ruled out the resistor as it doesn't work even in the "high" position. That leaves the motor or the controls themselves. I'm leaning towards the controls, cause the AC compressor isn't engaging and that circuit should be independent from the blower motor??? Anyways, if anyone has any insight or words of encouragement, they'd be greatly appreciated! Thanks in advanced...

-Keith

What did u figure out for the o2 code? I ask cuz I get the same code, but I've already changed both sensors and the cel still throws that code.

If there is no vacuum leak, Start checking the O2 sensors. Although, a vacuum leak can screw with the O2's which is why you need to rule out the leak first.

I guess to give more background I replaced my exhaust manifold because it was cracked, which is what started these problems for me. I'm hoping that its just not torque enough and needs to be tightened, or I bought bad sensors. And that the time it spent with the exhaust crack didn't kill the cat

Does your exhaust smell bad?

No I don't think so, I'll have to check when I get off

1. P0455. Evap leak. This can be something as simple as a bad seal on the gas cap. If cap is old, replace it and use a brand name like Stant or one from a dealer. There are a lot of el-cheapo caps out there that are not of good quality. If cap checks out okay, verify all vacuum hoses and connections coming and going from the evap. charcoal canister. If you get stuck with this code, many shops can perform a "smoke test", where smoke is introduced into the evap. system and where it leaks out is where your fault is.

2. P0135 is a fault in the "heater" circuit for the upstream oxygen sensor. It could be the sensor itself, BUT before you do anything else, under the hood on the passenger side is the Power Distribution Center (black box) that contains relays and fuses. Somewhere in that box is a 15 amp mini-fuse that controls the oxygen sensor heater circuit. Be absolutely sure that fuse is good before looking elsewhere. It is not uncommon for that fuse to blow. Many have spent hundreds of dollars looking for the fault, when it was a simple fuse.

3. For your blower motor problem. Easy diagnosis. Try running a wire from the battery directly to the blower motor. If it works, the motor is fine and you have a controls issue. If it doesn't work with this technique, replace your blower motor

It smells a little hot (not unlike any other vehicle that has 161,000 miles on it) and maybe a little rich... but not rotten egg bad like I've had problems with in the past with other vehicles.