Mechanics

300M O2 SENSOR PROBLEM

1930 Chrysler 300

2000 Chrysler 300m with 80,000kms. Ok I resently bought this car and when I was driving it home after buying it the check engine light came on. So I looked and it was giving me the code P0134 which is a Right upstream O2 Sensor error. So I took it to a mechanic and he recomended changing out the old O2 sensor. So I got him to do it, and clear the code. Not an hour after it came back on with the same P0134 code. Is there a fix to this because I have heard of a few 300m's to do this. It runs fine, no rough idle or anything. Just can't stand to see that engine light and code on.
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Sdk_racer
August 17, 2007.



Yeah, you want to get that fixed regardless of the annoyance. It may be a defective sensor that was put in, have the mechanic double check his diagnosis and the sensor. It may also be a problem with the harness going to the sensor. If the problem is on his end, I would expect that to be a no charge. This is when having a trusted and ethical mechanic that you are loyal to really pays off.

Well I trust the mecanic as he is a friend of ours. He hooked up his OBD reader, and said that both sensors (new and old one) seamed to be running the way they should. He just fiqured the old one could have been a worn out so it could be the cause. I don't think it's the senor in itself but the wireing harness going to the sensor might be the cause.

I ran across this on a different site.

"Oxygen Sensor Problem
On some 1995-1996 LH cars, the Malfunction Indicator Lamp may come on, and be accompanied by a possible sag or hesitation or rough idle problem. When you hook up a scan tool, you may find codes that indicate the right or left upstream O2 sensor is shorted to voltage. The cure here is not to replace the sensors, says Chrysler technical service bulletin 08-13-99, but to install a special jumper wire harness to correct the broken splice in the wiring harness. Ignition"

I know mine is not a 95 or 96 LH, but does this seam relevent to what my car is doing. Minus the rough idle that my car does not seam to have.

It is a Chrysler 3.5L OHC V6 Engine Service Bulletin

Tiny
Sdk_racer
Aug 18, 2007.
What kind of wave pattern are the sensors producing? The front ones should have SIN curve and the rear ones should be flat lined.

I'm sorry I don't really know.

Tiny
Sdk_racer
Aug 19, 2007.
Well, you can certainly guess at it and hope it works. And it may. The TSBs are pretty much unique to the vehicle sometimes due to a glitch in the manufacturing process or part problem during a run in the assy. Process in the bullitin you refer to, or so I believe.

While the symptoms match the cure may not. HAve your mechanic look at the wave patterns.

Ok, I'll talk to him about it in the next day or two. How exactly do you look at the wave patterns? Can you do that with the OBD reader or is there some other instrument to do this.

Tiny
Sdk_racer
Aug 19, 2007.
I would think your mechanic has a scanner that is capable of monitoring the wave patern. I'll try to post what they should look like tommorrow.

Well he has done some testing, but he is not 100% sure. But he thinks that the Powertrain Control Module is the cause. He said that it works fine for 10 or so minutes, then the O2 senser frezes up for a while and does not change readings.

Tiny
Sdk_racer
Aug 31, 2007.


http://www.2carpros.com/forum/automotive_pictures/30961_o2_waves_4.jpg



The bottom pic is how the waves should look. I think I would stay on the path of the O2 circuit before getting into a computer. Maybe run the car up in the air and monitor the wave pattern, while someone wiggles the harness to see if you can make the pattern change. Maybe tap on the sensor and look for a response. Maybe a defective sensor.

Ok well he did more testing and we decided to go for the PCM. It's been installed for a week and 450kms and no problems at all. I'm hopeing that was the cure. Thanks for your help.

Tiny
Sdk_racer
Sep 9, 2007.
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