So I have this code for bank 1 upstream chip........
1. replaced all sensors upstream and downstream with new Denso. still P1646
2. switched the two upstream sensors. no change
3. switched the two lower ones to see if anything changes. no change
4. borrowed from a neighbor that has a 2006 s type v8 and installed my sensors on his and his car did not show any codes. Installed his on mine and showed the same 1646 code!
5. Checked the connections and the voltage is per the repair chart that is available here.

History the car had a blow head gasket on that side so water did get into the exhaust. Could it be that the catalytic converter is bad?

Car has no other codes, runs flawlesly. Gas mileage is good!

the only thing that I can come up with is to replace the cats with new ones. Did anybody run into a similar problem?

I have read all the threads out there and in all cases it seems that replacing the 02 sensor solved the issue but in my case it did not!

Any suggestions and input welcome.....at this point even sarcasm!

 

Ideas:
check whether you get current flowing in the heater at similar amps for each (upstream) sensor
check electrical guide to see how the wiring is done, especially any grounds and splices, and for both heater & sensing circuits (the good news: you can compare banks)
JTIS probably has pinpoint tests, study (or figure your own) and carry out (a bit painful as eventually needs the PCM out)
there may be OBD data that helps (or may not!) - maybe freeze frame and/or live data


You can't swap the PCM at all easily as it's part of the security.

 

To add - check all associated fuses to the O2 sensors - might have blown w/ water being introduced into the exhaust???

As JagV8 mentioned - you will need to take on the painful task of electrical testing - check for voltage to the heater circuit upon start up. But I would check the associated fuse for the O2 heaters first. Also check wiring loom - you may find a loose, broken or shorted wire to the O2 heater circuit.

I don't believe the cat converters being bad would not throw the P1646 code.

If all else fails - maybe tap into the heater wire from the other upstream sensor and run across to the offending sensor heater wire - but I'm sure it won't come to that...

 

Good troubleshooting but you have your answer??

You need to follow up and see if the O2 sensor heater circuit is getting power from the electrical harness. It should not if what you posted is true.

Do you have the electrical diagrams for the car?

If not PLEASE get them!!

Follow the instructions in this thread and report back with what you find. It's for an X-Type and I can't guarantee it's the same but it should be close. Plus there are instructions on how to get the JTIS which is MANDATORY if you are going to do your own work!


https://www.jaguarforums.com/forum/x...pe-2-5l-88573/
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First I would check the fuses like a member mentioned before. Then I would have a real good look at the exhaust manifolds real close to make sure that is not cracked anywhere. Cracks are like hair lines so don't think it would be that obvious. After checking for cracks you can also make sure all bolts are tight in the exhaust. Then is time to start checking if the connections to the computer are good. I would check each pair with an ohmmeter to see if you see some resistance and that is similar to the one on the opposite side.That's how I would tackle the problem...

If I had to guess you have a hair line crack on the exhaust... seen it before.

 

No. A cracked exhaust manifold has nothing to do with the O2 sensor heater circuit. Stay focused on your problem.

Again you have done a good job troubleshooting you just need to continue. The car is telling you the problem with the error code.
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I tend towards agreeing but... techs often know things I don't. Is this one of those times? I don't know!

 

replaced the 30A fuses 20 and 35 with new ones and new R2 relay. Still the same code.


I think I have reached the end of my electrical knowledge.

made an appointment at the dealer for tomorrow morning. Willl keep you posted on the outcome!

Thank you for the fast replies.

 

Im sorry he is right. This is only for a heater problem, a cracked manifold would set other codes I apologyze. Let me give the official Jaguar procedure as a form of apology... in other words, this is what the dealer is going to do. (see attachment)

The dealer is going to hook up the tool, see the code, click on the code, and get this (see attachment)

Since I diagnose O2 sensors all the time I usually do it the way I described, and checking for cracks on the exhaust manifold is a must, but I have to admit I was wrong as that code is only for the heater. Hope the attachment helps.

In case the attachment seems confusing this is in easy words what they are trying to tell you:

Make sure that the wire on the heater power side is not broken from the O2 sensor to the computer

Make sure the wire is not shorted to the chasis of the car

Make sure that the cable is not shorted to the battery (the supply is 5 volts, shorting to battery would be 12 and mess with the computer)

Make sure that the wire on the heater ground side is not broken from the O2 sensor to the computer

Make sure the wire is not shorted to the chasis of the car (don't see how this would be a problem)

Make sure that the cable is not shorted to the battery

Best of luck!

 

That is a good check list! Is that from the JTIS? It looks different?
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feeling in a giving mood right before Christmas but normally do not look up info like some people PM and think Im here to.
there are no permanent grounds for the circuit, you have a fused power to 02 sensor pin1 WG wire should be hot when you turn key on.
Circuit on wire(switched ground) comes from the ecu RU wire, pins PH001, and PH002. use a DVOM low impedance to check DO NOT USE A TEST LIGHT or you risk blowing a ECU circuit. You should have ground with KO. back probe with appropriate back probe pins. Never front probe connectors or you risk spreading pins and creating new problems. You also need to check for continuity on these 2 pins to the 02 sensor pin 2 RU wire. I suspect you probobly have a bad heater driver(switched ground circuit) in the ECU from info so far and experiance and will need to pull and send out for repair and these tests showing a good wiring circuit would confirm this.

 

A possible ECU problem??

That has been a pretty rare failure. Hope it does NOT get more common.

Brutal I don't know where you can send a Jaguar ECM for repair? Will Jaguar do it?
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Maybe bba-reman

 

Rebuilt ECM, TCM, & ECU | Cummins, Dodge, Ford ... | Go ECM
ModuleMaster rebuilds ABS modules for as low as $100, 2 day average turn-around, 5 Year Guarantee

 

Well Ho Ho Ho and Merry Merry

Thank you Brutal for your input as always its much appreciated!
Merry Christmas and a Happy New Year to you!

 

The problem was ECM related...don't know what they did but the check engine light is off so will see in a week!

Thank you all for the input and Merry Christmas to all!
Andy
1SG US Army Ret.
1988-2010

 

Techinfo. Couple of thousand dollars a year :/ but I have something Jaguar related to read everyday