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Kia Spectra Engine Check Light

My trusty KIA SPECTRA 2005 four door has been a trouper for 163,000+ miles with only a few maintenance issues, mostly normal items that all owners face. I regularly change the oil at 3K intervals and timing belt every 65K and it’s been good thus far. It has average gas mileage and that has stayed the same throughout its lifetime. It runs well, but now this engine check light thing is driving me nuts! I used a scanner to find out the code msg and it indicated that it was a failing O2 sensor so I replaced both the upper and lower sensors, reset the ECU and while the light does not stay on it fluctuates between “all fine” and “hey we still have a problem here” going on and off at different times in the day. I then did a mini tuneup with new filters and Iridium plugs but broke one of the plug sockets off in the deep well of the spark plug cylinders and like to never get the end off the old plug, what made it worse is that it was impossible to just remove the plug because its deep inside the engine (not like I’m used to on other cars like the VW bug). Finally found a pair of needle nose pliers that were skinny enough and long enough to reach in and remove the end and strands of wire. Well that did’nt help either although it was proabably next on the list of PM items so no harm. Next I decided since I replaced the air filter, why not clean the MAS sensor as it’s also part of the fuel ratio system, so did that with a can of MAF cleaner replaced the boot and tried again, ah maybe that was it… NOPE! Just a little after two stops down the road and 15 minutes later the check engine light comes on again with the same O2 sensor code. OK, maybe it was a bad part, reluctantly order a second upper O2 sensor as this is where it all started and the code reader confirmed. A week later I have the part and it’s time to try again. Change it out and Volla! No engine check code… The another trip and a few stops, about 1 1/2 later, Yooo Hooo… Honey I’m Back did you miss me? The KIA greets me again with another pass at the same “check engine” code. Iyeeeee! Lucy goosie KIA, "What are you trying to do to me…Enough!!! The while the car seems to run and drive normally, no hesitation or smoking, no other faults or symptoms to mention. So I’m at a loss for what could be left.

There are a few O2 sensor codes. What is the actual code that keeps popping up? It will be in the form of P0xxx.

What’s left is to put tape over the check engine light and drive this puppy into the sunset.

The code is for the upper (pre-converter) O2 sensor. Low B- voltage intermittently, have cleaned connections at the contacts twice with contact cleaner. nice clean metal. Wondering if it could be a flakey ECU (but engine runs well) or is there a problem point somewhere in the wiring harness common to this model that I should be looking for? If so where is the most likely point? Sensor side all looks good, solid and clean. What could cause the O2 sensor to read intermitantly, considering that I’m now on new sensor #2 with the same results

In comparison could it be some issue like on a Ford F150 with harness wear issue with ABS speed sensors connections being stressed if the wheels are turned to their extreme positions, wearing the cable at the feed thru connect point. In this instance the ABS light blinks erratically on, stays on and the goes off. Its a known issue on older trucks. Could the KIA have a wiring issue unique to the O2 sensor?

Please list the exact code number that you are getting. As @BustedKnuckles has already stated…there are several oxygen sensor codes. Just because you got the code does not necessarily mean that specific 02 sensor is bad. There are a myriad of other problems that can cause a CEL to come on. My brother changed a couple of different 02 sensors and I finally tracked down the culprit…a dirty air filter. The CEL system is far from perfect. You need a good mechanic to find the actual problem.

UPDATE - The orignal code that I was receiving before changing the PRE CONVERTER O2 sensor was P0141, sensor heater malfunction bank 1 sensor 2… but now after replacing the sensor a second time I at first got the P0141 code, it went away, came back, went away, now the light is off, but the reader says that an error code P0036 now exists, H02S heater sensor circuit bank 1 sensor 2 however the engine check light is still off and has not returned for the moment. Same error? Different code?

I’m now on the second replacement O2 sensor, so thats why I wondering if I need to look for wiring issues or know failures with this model at high mileage over 160K, connections, other points of failure.

Also read somewhere that I can hit the cat, engine and exhaust with an IR thermometer to see if the converter is functioning, clogged or has gone bad, see the temperature differential. If I’m right it sits in front where the front PRE O2 sensor screws in and is part of the exhaust manifold (one piece), then connects to the exhaust pipe where the POST O2 resides and then on to the muffler.

P0141, sensor heater malfunction bank 1 sensor 2..
Sensor 2 is after the cat not the pre converter sensor you can see from under the hood. It is the one you refer to as the post cat sensor. I think you have been messing with the wrong sensor.

Are you using aftermarket o2 sensors? They can cause problems and look like you didn’t fix it.

A SIDE NOTE: The only other thing that has happened recently is that the outside temperature has dropped from the 80-90’s to in the 50-60’s during the days. Not sure if the ambient temperature can also have an effect on the results of any testing or troubleshooting, though I’d mention that as well.

I first replaced the PRE converter O2 sensor, then had the POST converter O2 sensor replaced, went back and replace the PRE converter O2 sensor a second time. I used after market O2 sensors in both locations.

So is there an easy way to check the sensors out of the vehicle? I have the original parts PRE and POST and the one PRE aftermarket part that I replaced.

Squriely thing is that I can’t tell any perfomance issues with the car, just the darn light coming on and off and the issue of having to pass an state inspection coming up very soon for next years tags.