Fellow enthusiasts,

I have extracted a trouble code DTC P1647 from my 2001MY XJR. Cleared codes, got a pending repeat code on short test drive. MIL light has come back on again confirming this is not a transient fault.

P1647 Linear O2 Sensor Control Chip (Bank 2).

Q1. Which side is Bank 2?

Q2. My Jaguar CD manual lists DTCs up to P1646 in the section on Electronic Engine Controls (303-14). Nothing in 303-07 Ignition, or 303-08 Emissions and nothing in the section on exhaust system. Can anyone tell me where I might get some further clues on this one?

At this stage I'm not sure if the term "Linear O2 Sensor" means the heated (upstream) O2 sensor or the un-heated downstream catalyst monitor - I'd be inclined to think it is the heated one.

Could the term Control Chip mean the O2 sensor heater control? There is a pinout procedure for checking that.

Q3. Can someone please please tell me that if I have to renew an upstream O2 sensor I don't have to disconnect the exhaust for access?

PS Car still runs great - no symptoms other than MIL/Check Engine Light.

Memoscan U581 Code Reader ordered yesterday so I can at least keep clearing MIL without troubling my friend for use of his U381...and I guess I should be able to freeze frame some O2 sensor data.

Happy Motoring.

 

Good info here,
https://www.jaguarforums.com/forum/x...37/#post370182

 

Thanks Sean B for the reference and XJRGuy Steve for sound input.

Finally got around to revisiting my warning light problem which was a code P1647 Linear O2 sensor Bank 2 fault.

Followed Steve's good advice and checked resistance of silver pin-outs on left (bank 2) and right (bank 1) upper (grey) 02 sensor connectors. Left (fault code side) gave open circuit (high resistance) where right gave closed circuit (low resistance). That says left bank sensor heater element is toast.

To verify, I switched left and right bank connectors, cleared codes, then went through start up cycle, which is normally enough to set the code after clearing. With the connectors switched the light came on but this time with a code P1646 Linear O2 Sensor Bank 1 fault. This confirms to me that the upper left sensor is at fault. As far as I can see the wiring pigtail from connector to sensor is not damaged...though it is very difficult to access.

So I need to renew the upper left sensor...which on a UK spec right hand drive car is the worst one to get to, of course. At least I'm confident of what has to be replaced - many thanks.

Happy Motoring.

 

Hi Munro
Just bought a 2001 XJ8 with the same problem. The work sounds a bit daunting! Before I take the plunge can you tell me approximately how long the job took and if any special tools are required?

 

I had this problem on my 2001 XJR a couple of years ago. The fault code P1647 simply means that the heater element has gone open-circuit (burnt out) on the O2 sensor.

These sensors are not the usual 'switching' type of O2 sensors-they are actually Wide Band Linear air/fuel ratio sensors. They have to work at very high temps & so have a much more powerful heater element-which is prone to burning out at high mileages.

The resistance of the heater element is typically 1-2 ohms & they draw a very heavy current, which is controlled by the main ECU.

P1647 on UK cars refers to the sensor on the passenger side of the vehicle, which can only be accessed by moving/removing the coolant expansion tank & then the exhaust heat shield. Basically, you have to remove whatever's in the way & it's a morning's work.

The new sensor is very expensive from the dealer, but you can get the actual part from Jag suppliers on ebay for a lot less.

One very cheap fix is to buy an old 'grey plug' sensor off ebay from the X-Type 2.5L & 3.0L V6 models-these are a similar type of sensor & do work on the X308's...

Most failures are the P1647 code, and I suspect that this is because that particular sensor works in a more confined & hotter location under the coolant expansion tank. The other sensor which give the P1646 code is more exposed to airflow & so probably runs a bit cooler-hence doesn't fail as often...

The job will take at least a couple of hours & probably all morning if you've never done it before. It's tight location to work in & there isn't much space-the coolant expansion tank needs to be removed & so some coolant needs to be drained off first. I found the cleanest method was to shove a long length of windscreen washer tubing right down the expansion tank into the lower hose part & then syphon off enough coolant to fill an empty 2L lemonade bottle.

This drops the coolant level enough to allow removal of the expansion tank without a big coolant spillage. You will also probably need to move/remove the adjacent heater hoses to make enough space to remove the heat shield & access the sensor.

The 'Crow's Foot' sensor removal tool can be slipped over the electrical cable & onto the sensor. Then the problem is leverage, as there's not much space to get any decent amount of leverage on the wrench you attach to the sensor removal tool...

Hence allowing a morning for the job

 

Just went through this with my 99 XJ8 Sport. P1647 is the upstream Oxygen sensor on the left hand side; that is the driver's side. I ordered two Bosch from a vendor on Ebay for about $62 each and replaced both. Problem solved. On my car there is a heat shield which was a bear to work around.

 

Gents,

My diagnosis was spot on, but I was not confident I could get in and remove the upper left (bank 2) sensor, especially with the heat shield in place.

So I took it to the shop where they charged me what appears a reasonable £250 sterling to supply and fit the replacement. All fixed....now, what's next on the list...

Just like to say once again thanks to Sean B and XJ steve for great advice. Even though I took it in to be done in the end, I felt confident I knew what was wrong and how it ought to be fixed. If the diagnosis had flagged any of the other three sensors I'd have done in myself and saved paying a couple hours labour.

 

Just started the removal of the upper passenger side sensor on my 2001 XJ8. A couple of tips for what they are worth:
1. Removing expansion tank: I extracted all the anti-freeze using the trigger-action squirt head off an old bottle of spray weedkiller. They only get thrown out anyway and are ideal after a rinse out. Stick the tube way down the bottom hose via the tank and you won't spill a drop of the 2 litres of fluid you can extract. With the tank off you can do the same down the open neck of the hose.
2. Be VERY careful unclipping the hoses at the top of the expansion tank. One of mine snapped and a kit of three for nearly £50 is the best I could find.
3. With the hoses all bent out of the way the heat shield can be easily extracted out of the car. The bracket is only 2 bolts and easily lifted.
4. Do NOT buy the US Pro sensor tool with built-in handle, like I did. No room to use and no room for leverage. An expensive mistake at £15+ for a tool which does not fit well either.

Now....anyone with best advice on where to buy the new sensor in the UK. British Parts want £150 - £180 !!!!!

BTW....can only find one grey four wire plug above the transmission, which leads to this sensor. The plug next to it is black. Does that sound right?

 

The upstream sensors have grey plugs, while the downstream sensors have black plugs. On my 2001 XJR there are 4 plugs in a bank above the flywheel bellhousing-2 grey & 2 black.

The cheapest I saw a new sensor priced at was around £120 off an ebay supplier of genuine Jag parts.

If you really are strapped for cash, you can actually use a second-hand grey plug upstream sensor from the X-Type 2.5 or 3.0L V6 models as they do work in the X308 V8 models. You can find these on ebay for around £30-maybe less, depending on how lucky you are...

 

IT JUST GETS WORSE....AND WORSE....AND WORSE!!!!

For those who want a good old laugh, or who can offer advice and sympathy...I would like to tell you how my "simple saturday morning" O2 sensor swap turned into a catalogue of errors and ended up taking me over a week to complete.

P1647 code: so I started to take all the expansion tank hoses apart and tried to take the sensor out with an inapropriate tool as described previously.

SO, I ordered a new tool off n&mparts on ebay: a draper 90mm socket with 'window' for sensor removal. Four days later they sent me the 150mm long one by mistake - way too long to use. (Can I get a refund off them!??!...no comms, no refund!).
Luckily I also bought a set of offset sensor sockets, which proved up to the job. After a 5 day soak in WD40 the sensor was still very difficult to shift. But, 2 hours of swearing and bruised knuckles and it was off.

Next I ordered a replacement sensor off Jaguar Recycling in Wiltshire via Parts Gateway website. Four days wait, and you guessed it - he sent me the wrong sensor. His plug was completely different to mine, despite all the Denso listings showing the same plus as mine. I called him up and he told me there was no such plug as the denso style one on any of these Jags and all the other dealers have got it wrong. Despite only sounding about 12 years old he claimed to have sold thousands of these parts over the years and never heard of one like mine. "My car must have been rewired with the loom off an S-Type" he said. (1 owner, full jag history -- I don't think so!! Promised me a refund, but you guessed it - no money back on my Barclaycard).

To test the car out while I await a new sensor, I took the upstream one off the drivers side bank - an easy five minute job to swap out later - and put it in the other bank so I could put the expansion tank back and run the car. I am now getting a P1642 code proving the sensor is the faulty component. SO FAR....SO GOOD!!!!! YIPPEEE!!!!!

So I thought! Started the car up and I now get several new codes and lights:
P1638, P1642, P1000, P1637, P1643, P1646 plus red and amber warning lights over the warning display. ABS and red Brake symbol on the dash and scrolling messages saying "RESTRICTED PERFORMANCE", "LOW BRAKE FLUID", "GEARBOX FAULTY" and other brake related codes. Sometimes the car will not let me select a gear.

My code reader clears the codes by they persist. I suspect electrical comms issues rather than mechanical fault.

I am sure none of these are actual faults with the cars mechanical systems because there was none of this before I tinkered. Braking is good and the engine runs fine.

I suspect I may have got things wet because I was trying to work on the car outside the garage and got caught in a shower before I tented a car cover over myself and the bonnet so I could work under cover.

Any advice???? I have had the car about a month now and hope not to have it in a month's time. I just want to sell up - cut and run!!! But I have grown to love the Jag...it just doesn't love me back!

 

P1624 is not the fault code for the other bank sensor-it should be P1646.

Make sure you disconnect the code reader before starting the engine-the fault codes are meant to be erased with the ignition ON & the engine OFF. If you leave it connected & run the engine or drive the car, you'll get all manner of weird fault messages appearing which get progressively more serious-although there isn't actually anything wrong with the car.

Ask me how I know

If you swap the O2 sensor from the passenger side to the driver side (UK cars), then you'll get P1646 instead of P1647.

 

Thanks "Red"
You are quite right of course - it was a careless typo on my part. Having the car reassembled and back on the road with the sensors swapped over I now only get a P1646 code, proving that it is the sensor which is dud. But at least this will now be an easy 10 minute job to fix.

The next dilemma was finding the right part (Denso 192400-3101 as fitted on my car) for the right price!!! Most used parts are not compatible due to plug differences. Most internet sales are asking virtually £150 - £200 for the part. I managed to order one from www.worldcarparts.co.uk for half price. It should arrive tommorrow then I will be ready to "rock n roll".

Without this forum I would have probably been in for a garage bill of £400+VAT. With your help it's cost me about £100+ and I had the satisfaction of doing it all myself.

Thanks fellas!!

(Now for a thread about why my rear number plate lights won't work......hmmmm).