his is a repost from the tech section

Hi all, I've been having a problem recently with hesitation which I thought was a fuel filter problem. I've had a check engine light on for a month or so also. I had the fuel filter replaced yesterday and cleared the codes. I drove all day yesterday and it ran like a dream. Smooth acceleration and smooth idle. No check engine light either. I stopped today to fill the tank and immediately after leaving the station, it started sputtering and the check engine light came on. It ran rough all the way to work.

Has anyone experienced this? I'll check the codes tonight when I get home and plug in my code checker.

Thanks!

Allyn

 

OK, just ran my code checker and it comes back 1138 and 1158 Lack of HO2S12 and Lack of HO2S22 Both are Rich.

Seems like a sensor problem.

On a side note, the check engine light had never come on before I changed the trianary switch on the high and low pressure side of my AC with the Jag workaround. Can it be related in the wiring harness?

Again the engine light stayed off when I drove it today until I filled up...weird!

Any ideas?

 

After further testing, I've repeatedly gotten 1138 and 1158 Lack of HO2S12 and Lack of HO2S22 Both are Rich Codes. In addition, I get a P0300 (engine misfire) code. The engine runs rough and then smooth for 10 minutes and then rough again. I've refueled a few times and it seems NOT to be consistent with refuels as first thought. I am going to replace my plugs and wires as they have never been changed since 1995.

Should I be checking the coil or something else???

Thanks,

Allyn

 

Your codes represent a lack of "swing" and are not just rich condition. I do not believe a coil is your root cause, since misfire will cause lean lambda readings. And, yes, your codes may very well be harness related. I assume you also noted that the possibility of swapped lambda sensors is also given in the possible causes.

 

Thanks Sparkengap. I should have mentioned that the valve cover gasket was changed this week also. I know the mechanic had to most likely remove the plugs and wires to remove the valve cover. The problem has worsened since getting it back this week from that operation.

Allyn

 

Believe it or not, the harness connections for the lambda sensors on an X-300 are not absolutely defined. There is a difference in one of the wire colors, and the diaagrams show a "preference", but there is a dealer software procedure called "orientation", run with WDS, IDS or other high end software that figures out which sensor is connected where. If you are not connected the same way as when it was oriented, all h*ll breaks loose!

 

I will be replacing the coil boot covers and plugs this week. So far the car has run very smooth for two days and the check engine light hasn't come back on????

It's been warm and dry...maybe moisture when the valve cover gasket was swapped???

 

Replaced the coil boots and plugs. The engine runs much smoother. I don't get anymore "misfire codes". I have on persistant code P1138. I clear the code and can drive from 20-350 miles before it comes back on.

Can anyone tell me where that sensor is located? maybe just be easier to replace it.

Thanks all,
Allyn