I started the car the other day (2003 XJ8) and got the check engine light (CEL) but didn't have my code reader with me (shame on me!), so I drove 22 miles home and then checked the code -- 1647. I had no trouble driving home, I even stopped and restarted the car a couple times to see if it would clear the code (I hate driving with the CEL illuminated!).

Ok, so I start reading on the forum about 1647 codes and found that there is a slight chance that it could be a problem stemming from improper re-installation or hook up after having my transmission rebuilt, and that's going to be the crux of my question.

First, however, let me mention that if I clear the code with my code reader, it doesn't come back on while driving the car, and doesn't always come back every time it's restarted, but in the past couple days, it has come on several times only when starting the car. I can clear the code with the engine running and it never comes back while the car is running, so I'm assuming it (the CEL and code) have something to do with the initial diagnostics, not with actual failure of the O2 sensor (rash assumption?).

So, now my question -- or rather request for advice.

Should I take the car back to the guy who R&R'd the transmission and ask him to make sure he re-installed/connected the sensor properly, or is that just a waste of time? It's not convenient for me to do so since he's in a different part of town and he'll want me to leave the car with him for a day or two.

Just wondering what you guys/gals would say about this. The transmission was R&R'd just after Thanksgiving and I've put maybe 300 miles on the car since then. Thanks.

Mike

 

hi old mike had the same poblem when I had the tranny replaced. found out they plugged bank one sensor into bank 2 and so on. one of the sensors was loose, ended up haveing to change two of them.I bought them from Oxygen sensors .com they are the cheapest . the upstream sensor $152.41. down stream $66.97 they are Walker sensors had no poblems since.. hope this helps.... plus free shipping

 

Quick note: I'm guessing you mean P1647. There are also C1647, U1647 and so on.... That first letter is vital.

 

OBD scanners read engine codes, not chassis or trans, so it's safe to assume Mike means the engine.

Mike have a look down behind the engine and eyeball the connectors yourself. There's a few threads on here that show their place and colour codes, 2x grey on your drivers side and 2x black on the passenger side. If the colours are in the wrong place you have your answer....

 

I'm so sorry -- yes, I meant P1647.

 

I will have a look, after I search a bit to figure out how to do that. Thanks for the help. I'll report back after I have a chance to check it out.

 

After reading some posts, this one in particular https://www.jaguarforums.com/forum/x...sensors-55786/ , I can see that this might be a real PITA, however I will try to eyeball the driver's side sensor tomorrow when the sun comes up!

 

Ok, what exactly should I be looking for? If I'm reading correctly, the P1647 code is for the O2 sensor on the left side (drivers side, US), but is it the one that is higher up or lower? And, what is the 2X grey supposed to mean?

I could see the sensors, just want to know what I should look for before making any rash decisions to buy new ones or going back to the mechanic.

Thanks.

 

bank one passenger side bank two drivers side. unplug top grey sensor upstream then change it with the other upstream to see if you get the same P1647 error code,if so the bank two sensor is bad do not forget to put the sensors back in the right order..if you look at plugs you will see upsteam sensor has the tang on the right side of the plug. down stream sensor the tang will be on the left side. some of the down stream sensors can be grey also

 

I don't mean to be an ingrate, but is it really worth the trouble to swap them out, or am I just putting off the inevitable -- replacing the upper o2 sensor in the driver's side?

I'd like to check the connectors, but I was unable to even see where they plug in! Should I be trying to access the plug from underneath the car or should I be able to do it from above? Do I need to just start taking things off (like the coolant tank, not my clothes! LOL) and stop putting it off?

Thanks for all the info.

Oh, one more thing -- unless I'm going to go to the trouble of swapping them, I would guess I should go ahead and order a new one -- any suggestions? Welsh has the upper one for $155 -- seems a bit steep, but it that's what it costs, I'll just go ahead and order one.

Ok, one more thing -- it's either my imagination because of what I was reading on this site, or my gas mileage has really taken a dive! I'd like to get this fixed if just for that issue alone! I could pay my mechanic $75 an hour to replace the sensor and still be money ahead.

 

sometimes P1647 is caused by dripping injectors: try cleaning the MAF sensor, the throttle plate and bore, and run a bottle of GUMOUT's best through a tank.

But if the plug to the sensor is not tight, that will be the cause of the code: cleaning up the fuel air delivery should help the MPG; if it has gotten cold down there, that will also contribute to lower mileage.

 

Thanks Jim, I'm going to try to see if I can find the connector to see if it's tight. I have yet to figure out how to get to it, but where there's a will, there's a way!

I only mentioned the gas mileage because I read on here that I could suffer a decrease when the O2 sensor isn't working properly.

 

Some do, but most read all codes they can find in the PCM. Some read all codes in many maybe all modules.

Seems worth putting in the proper info as sooner or later someone leaving out a letter will get bitten.

 

Jim -- thanks for the tips. I would love to check the plug but can't figure out how to get to it without ripping half the car apart!

I thought I'd mention also that my code reader says I have three codes and then it displays P1647, P1000, P1647 p/d (pending). Does this shed any light on the situation? Also, the CEL comes on a few seconds after it goes off subsequent to the initial diagnostics.

In anticipation of buying a new one, can anyone give me a part number or source for it? Thanks.

 

Mike, check out this thread -
https://www.jaguarforums.com/forum/x...0-p1647-89411/

It sounds like your O2 sensor may be bad, upstream, bank 2, that's the hard one. You do need to get under the header tank to get to it.

 

That was one of the threads I read -- in fact it's where I got the idea that my fuel economy was going down because of the bad O2 sensor. I'll see what I can do one of these days!

I did notice that the RH one is hidden under a heat shield, whereas the LH one (the one I need to get to) is easily spied without removing anything. I'll take the expansion tank off, even though some have said that they can get to it without actually removing it, but what the heck, I might as well take it out if it makes the job easier. I hope to be able to get to it soon, maybe not until next weekend.

 

It's often (always?) a 2-trip (meaning warm-ups of engine) code so if cleared when you've started driving it would not normally come back on for that trip. Possibly not for the next trip, either.

With the heat/cool cycles they can almost weld in so swapping side to side can be "challenging". Sorry for the bad news!

 

JagV8 -- thanks again for the info. I was wondering something -- not a big deal, but I'm eating lunch at my desk and got bored! If I clear the code, does the ECU think the O2 sensor is working correctly? If so, does that mean that by clearing the code I should be back to getting the superior gas mileage that I've always gotten with this car (NOT)?

I clear the code every time I drive the car -- it stays off until the next restart. The car seems to drive fine, but I haven't really compared the "CEL on" to "CEL off" performance. Might be interesting.

 

I don't know. After clearing the PCM wants to see the various sub-parts (OBD monitors) working (or not). It'll fuel as best it dares but how far it dares go I don't know. Its main aim is to protect cats and engine (so not run lean) and - if it can - to keep emissions down. MPG isn't on its list. Only if all monitors are OK and no sensors show faulty will it then do its best to get fuelling really accurate.

 

Still wondering if anyone could help me find the right O2 Sensor?

WelshEnt can order one for me for $225 -- wonder if I could do any better?