Have a 2005 Jag S-Type 3.0. Out of now here on Wed. of this after driving several miles in the middle of high heat 105 + of the day. A CEL came on. Every other time I have had this happen, it was due to a dirty MAF sensor. I would clean (which I did in this case and after a couple of drive cycles it disappears. That was the sequence of events on Wed.

No Cel for the rest of Wed. and none on Thursday. Drove about 20 miles today. No problem. Stopped for several hours, started car, drove several miles and out of blue CEL is on again, after mild acceleration on Freeway. Again temp was 105+ for he day. Went home, did a re-clean of MAF, checked air filter- everyhting fine. Decided to drive to O'Reillys just to check codes (my scanner is with a friend) and it shows 1646 and 1647. Drove home, made one stop, about my 4th time for stopping and starting the car and CEL is gone. Nothing appears wrong with car, although gas mileage seems down, but then I have been doing much stop and go at slow speeds recently.

What is the story about a coming and going P1646 and 1647 code and I do not know if the incident on Wed. I assume the Wed. incident was also a P1646 and 1647 as no other code was stored.

I see notations about o2 sensors and was curious if at 60k this was common or by chance if the heat of the day and the heat of the car would be a contributing cause.


What damage would any of these problems cause to the car or the cat or anything else?
Suggestions, ideas and any education on the mater.

Thanks

Tom in Dallas
2005 S-Type 3.0 60K

 

I believe those codes are specific to the O2 sensor heater elements, not particularly for running rich or lean as that could pertain to the MAFS. The high heat could be tricking the ECU into thinking that the sensors are too hot or the heater elements in the sensors themselves could be failing as a result of the heat. If the codes persist, I would recommend replacement of both upstream O2 sensors.

 

Thanks, I understand the difference about the MAF and the 02 sensors. I was just telling what had been my procedure previously and it was only on a lark, I decided to have the codes run today instead of waiting a couple of days for my scanner to get back to me.
It is common to have the O2 sensors being intermittent before failure. If they fail, or get stuck open or closed, how can my engine or cat be damaged or will it just result in low gas mileage. I have an extended warranty that will cover these, but wanted to know what sense of urgency I need to have to have them fixed. Will it ever send the car into RP or limp mode?

How hard are they to replace and where the devil are they in my car?

Thanks

Tom in Dallas.

 

Hi Tom,

Did you get your problem resolved? What was the fix?

 

Not really. Since I first posted this I still get the error and I have new O2 sensors from about a year ago (also new cats, new plugs, new coils) It only occurs when it is summer and very hot and I am driving in bad traffic. The O2 heaters are not even being used at that point and it is just a test to the heater element. Sometimes I see a CEL and it then goes away quite quickly after 3 or 4 starts, not to reappear for a time period. Never has happened except in hot summer.

I have monitored my sensors and live data with the scanning tool and they are doing what they should do. I have never had the heater ever not work from a cold start or ever generated a code at that point. Sometimes I can look at pending codes and see them and then they go away.

Whether pending or confirmed they could be 1646 alone, 1647 alone or both (which I find strange as I thought if the computer saw a 1646 it would not test further to get a 1647). I am using the Denso O2 sensors ( DENSO 2349030--http://www.oxygensensor-crossreference.com/convert/jaguar/C2C29250 ), which are essentially the original since Denso owns NGK.

So no answer, only a mystery. I have no breaks or crimps or chaffing in any of my wires and the relay and fuses are fine.
The car run great minus a very small tremor (I even hesitate to call rough idle- but sorta) when I am in idle and the compressor comes on and the rpms dip a touch.

If you have a suggestion, I am more than open. This will happen whether I am at p1111 or p1000. Go figure and since I am a touch OCD on these things, it gives my warts of worry a slight workout. Are you also having or have solved this issue?

Thanks

Tom in Dallas/Plano
2005 S-Type 3.0 85k

 

Our problems are similar, our vehicles are slightly different.

I have all new O2 sensors, 90% of the harness visually checks out, no visual signs of ecm damage, so far 4 grounding locations check out good.

On our similar problem I've read:
1 report of a short fixed in the harness with no location info.
1 report of a bad ecm.

Next step for me is to properly diagnose the ecm.

Thank you for the update.

 

I noticed that you are getting some other codes than I am. I would be hard pressed that the ecm is bad at that one point, unless you have had a water problem that you are unaware of. Mine is intermittent and at times that the o2 heater would not be used and only in 97-105 degree weather after the car is heated up and in traffic. Below 90 degrees it never happens and they work at the only place required- at startup.

Anything else you can find, I would appreciate knowing. Yours seems to be a problem with all 4 and that might well point to some common connection point. You can have the ecm rebuilt at several different locations and I would suggest that you find an independent that has Jag experience and the jag software to get into the back end of the ecm we can not see on normal scanners. Stay away from the dealerships. They, beyond, expense, arrogance are the worst diagnosticians I have ever seen. If they were in the medical profession, they would be in jail for murder.

Tom in Dallas/Plano

 

I'd go for an intermittent loom or sensor rather than a bad PCM, say 90% or 95% of the time. You could data log (i.e. record) and see what's going on.

 

Have you seen a bad O2 loom before? Was it cracked or were the wires not making contact all the way through. If it were a loom, what would you suspect and in the case of 03Xtype's car -would he have all 4 looms bad or is there a common connection before going to the ecm/pcm?

What about mine on the upstream- is there one connection common to just those before going to ecm/pcm?

Tom

 

You can tell a lot about the way the loom is made by inspecting the electrical guide (and maybe also JTIS) but after that it's down to checking the looms.

The other guy looks to be in the wrong forum...

 

With all the heat and everything else in the area from the road, there is always a possibility of oxidation in the loom or connections in the loom. I may well trade out the sensors on warranty and use a good electrical connection cleaner and see what happens. To me it is strange that it happens in only certain specific conditions and then will disappear. If it happen year around and all the time, especially at startup- that is one thing, but the conditions I see make it very strange???

Tom in Dallas

 

A small number of S-Types have had corroded looms with weird faults resulting. I think the looms had been pierced so water got in.

The one a few have mentioned runs behind the front bumper and up high in the front wheel well(s) ("arch(es)", for UK). You'd have to study the elec guide to see if it can affect the O2s.

 

Treat me as a dummy now. What loom are you referring to and where is it located? Loom is a broad term. Are you talking about the plug in connector from the O2 sensor or what? Are you referring to the entire wiring harness? The most often one I hear about is the heater control valve to the CCM, but that has nothing to do with my issue.

Tom

 

Look at the guide. It shows multiple large (as in fat, many wires) looms and where they run.