Dear all, i've a cherokee sport 2001 4.0L. My check engine light came on with an O2 sensor 1/2 code. After i cleared the code the CEL didn't turn on for about two days of several trips. The third day i was in a traffic stop and the weather was warm then the CEL showed with the sensor's code. Then i cleaned the sensor and cleared the code. Two days later the CEL appeared again. i drove for about 30 miles then the CEL turned off by itself. One day later when i was in a traffic stop, i turned on the AC and the CEL showed again with the O2 sensor's code. Does anybody know what is happening. Thanks in advance

 

How did you clean the O2S? Oxygen Sensors generally don't take kindly to being cleaned.

What did the O2S probe look like before cleaning? White? If white, it may be anti-freeze deposits.

You might try replacing that O2S. Below is a list of NTK sensors. Use NTK, not Bosch.

 

Vehicles do not fix themselves so erasing the codes multiple times isn't doing any good for your Jeep and cleaning an oxygen sensor isn't going to do anything to fix or repair the sensor. If you have any exhaust leaks, start by fixing that. If your exhaust is good and has no leaks I would replace the both oxygen sensors. And if the code continues you probably have a bad catalytic converter.

 

From beneath the car

 

I've cleaned the sensor using injection cleaner. I guess then i shall replace the sensor1/2 as i've already replaced the 2/2. I would like to ask another question please, the exhaust pipe after the two cats touches the oil pan (see the above image). Wouldn't that heat the oil up? Would it affect the oil life time? How do i fix this? Can i put a heat insulation such as fiberglass covered with aluminium foil? The oil pressure is ok with a max of 45 psi and min 20.

 

That's uncool.

See if you can unbolt the front exaust pipe from the manifold and move the pipe around to clear the oil pan. You might have to unbolt the rear Cat for more movement.

 

He has a 2001. It has four O2 sensors.

Regarding the pipe touching the oil pan, it's a common problem on the 2000 and 2001, but it's adjustable. Loosen the downpipe from the exhaust manifold and move it. You may need to loosen the next hanger downstream (I think that's at the transmission mount) to make it easier to position it. Then tighten it back in the correct position. If it wants to torque back over against the oil pan when you tighten the bolts, the donut exhaust gaskets between the manifold and downpipe may be crushed into that position and may need to be replaced. They're about $5 or $6 each.

 

Ive had bosh sensors for at least 3 or 4 years and havent had an issue with them.

 

Another Bosch country heard from.

If the OP has NTK O2S' installed from the factory it would be insanity to mix Bosch with NTK.

 

I wish I had thought of that....dang.

 

Sorry, didn't read yours before posting mine. Great minds and all.

 

I thought it was insanity to mix new 02s with old ones. If one went bad you can bet your *** the others are on their way.

 

I normally subscribe to this point of view, except that the 2001 has four O2 sensors and hence twice the cost of a normal XJ. There comes a point where it's not really cost effective to replace sensors not known to be failing. Some folks here are on a budget.

 

I know what you mean. I changed one 2 weeks later another one went out, 2 weeks later the other 2 went out. NTKs are ~30 each on rockauto. Thats not too bad. I spent way more than that at autozone.

 

Exactly.

There's a DTC diagnosis that points out a mix of old and new O2S's will cause the specific problem [being addressed]. I can't rember what the code was, but, yes, O2S's should be changed as a set.