First, I hope all friends and forum members are off to a good new year. Mine was going good until lol.

We had a couple of nice days here in South Carolina so I was able to get the Jag out for a few good 30+ mile drives earlier in the week. I completed a lot of work on the Jag starting last summer and the car is about where I want it to be condition wise (Think Rothwells thread) and it has always run absolutely flawless. I decided to give the car a well deserved wash and I did some engine bay detailing. While under the hood I popped open the air box and cleaned it out (filter was as new) and cleaned the MAF sensor with CRC MAF cleaner, also cleaned throttle body. When I was finished it was getting late but I still drove the car around around the block and all was well. The next day car starts and runs perfectly and then CEL illuminates?

Scanned codes:

P0308 Cyl 8 misfire

P1316 Misfire rate above limit

P1647 Bank 1 O2 sensor

First, I decided to erase the codes and do a hard reset. That got rid of the PO308 and the P1316. Actually all was good till the P1647 showed itself again.

Next I went back over my tracks under the hood looking for any clues and cleaned the MAF sensor again. Cleared codes drove car around the neighborhood and all was good. After sitting for 30 minutes I restarted and got the P1647.

Few Things: Battery is always on a tender and never has been below 12.6v actually today was 12.7v.
Car runs and drives perfectly
Inspected O2 sensor wires (what I could see) they look like New.
I do have some data stream capability if that would help. To me it looks like B1 S2 output voltage is too low causing the 1647 code and illuminating the cell?

I'm finding it hard to believe that I didn't do something wrong lol. The timing is weird too


Thanks in advance guys!

 

It does look as if the O2 sensor has failed, which, in itself, is not unusual.

It doesn't sound as if the engine has gone into a restricted mode so I'd probably check the connector on the sensor by unplugging it and cleaning the contact with spray cleaner. Then delete the fault and do a high speed run to get the engine/exhaust hot and then check again. If the fault has returned during the run, then delete it again and see if it returns. If it does, it sounds like you need a new sensor.

Richard

 

Kind of what I was thinking Richard. The timing is bothering me and after reading a lot of old threads involving O2 sensors, fuel trims and MAFs being the possible culprit I was just looking for a little guidance (thanks).

***Update

After reading more threads I'm even more confused.

DTC 1647 is Bank 2 (drivers side) upper sensor which is not what the data is showing? Am I looking at it wrong?

Also found an old thread where Bob (Motorcarman) said that it takes two starting cycles for a DTC to be set and that is 100% correct. Because every time I cleared the code it came back on the next start up.

I will check and clean the plug end and connector and go from there?

 

Good luck and keep us posted....

 

Well what do you know maybe I didn't do anything wrong lol. After some choice words today I swapped the plugs on the upstream O2 Sensors and sure enough my DTC P1647 (bank2) changed to a DTC P1646 (bank1).

I found the correct upstream sensors Denso 234-9029 on Ebay for $80.00. I just haven't decided if I'm doing both sides? I contacted the seller to see if he has another sensor because for that price I'd do both. However, either way I am in the famous parts holding pattern.....

Just a curious note**** This O2 failure occurred after washing my vehicle the weird thing is in my research of old threads I remember reading a post or two where others had the same code after washing their cars. I can say without a doubt that no water touched any sensor connector plugs or the actual sensor on my car. The only reason I'm mentioning this is for the future members trying to figure out why they got a code after washing their car. My best answer is I don't know lol?

I'll let you know how it goes guys thanks

 

That's a very good diagnosis procedure. I wouldn't have thought that the connectors would be close enough to each other to be able to switch them around. I'll remember that. 👍

Richard

 

Just coincidence. When a part goes bad it's too easy to get wrapped up in looking for a cause rather than just accepting that parts just go wrong sometimes for no good reason.

 

Hey Richard

No Joy in swapping those connector plugs it's crazy tight back there but doable. You really have to take your time working between the firewall and throttle body;there are just too many things you don't want to disturb or break which can ruin your day really fast. So far so good I'll update when I get the new sensor. Take care.

 

I guess sometimes we just look for a reason so we can wrap our heads around a problem? It's funny, I agree, when I owned a shop I would laugh at people saying they couldn't understand why something just stopped working or failed. My line was always a light bulb works great until it doesn't. I guess that's also what happens when you read way too many old posts and try to look for a pattern.

 

Great line! I must try to remember it.

 

Well my sensor arrived and I got it installed same day. I decided to try getting out the old sensor with a pipe wrench because I was able to get a good grip on the flats and felt I would have a better chance of success than using a split socket O2 sensor tool.

Once a plumber always a plumber lol

Easy to get out with minimal damage to the sensor


When I installed the new sensor I used a little anti seize and torqued it in with an open end wrench which worked really well.
I cleared the codes and took it for a good 30 mile test drive with no more CEL after several start and drive cycles. 😎 ahhhhh all good

 

Well done....

 

Andrew, I'm doing a follow-up on the Denso sensor.
Here's hoping all is well and I ask because I have one that someone's car I work on got it for his car. Not needed and sold the car, I ended up with it and just stuck it on the shelf.
Guess who got the P1647 because I didn't drive the car enough, AGHHHH.
So, are you still good one the on the 9029?

 

Wayne,

I just checked my records on when I had to replace the Bank 1 Upstream oxygen sensor in Jan's 2006 XK8 (December 27, 2020). Her factory sensor was throwing a P1646 code. I ordered a genuine Denso 234-9029 sensor from Amazon for $93 and that indeed fixed the issue. No problems with it since then. Hope this helps....

 

Got to drive that car more Wayne.

 

Hi Wayne

​ ​ ​ ​ ​ ​ ​ About time you showed that O2 sensor a little love lol. My car has been flawless since I changed the o2 sensor the 9029. However, remember I have an 03 so I looked up the Denso sensors for your car and these are the sensors Denso lists.

Upstream: 2349016

Downstream 2344798

At least you have the correct part numbers if you have to you could cross reference to another manufacturer.

​ ​ ​ ​ ​ ​ ​ Anyways, all is good Wayne and I'm enjoying the weather while working on the cars and my house (it never ends). I hope you and Christine are doing well and hopefully you two are planing a trip down to NMB sometime soon.

 

Thank you, Andrew, the numbers are different, better get to checking the difference.
I'll get one, don't want to run that wire but once, that was the hard part.
We are talking about heading your way, I'll check in before hand.