Hi,

Went to pick up a friend from the airport today. Driving there went without any trouble. Filled up the tank before heading back and on the motor way I noticed the orange engine warning light was on. I had my ODB2 scanner connected all the time so I was able to check the fault code straight away. The code was P0037 (HO2S Heater Control Circuit Low - Bank 1 Sensor 2). I reset it a couple of times but it kept coming back. At home I checked the following fuses in the engine management fuse box (left side within bulkhead extension):

No: 1, 30A, O2 sensor heaters bank2 upstream and downstream.
No: 11, 30A, O2 sensor heaters bank1 upstream and downstream.
No: 14, 10A, O2 sensor heaters relay + other stuff.

All fuses were ok. I don't know where these sensors are located so I haven't been able to check them. Is there something I can do or is this a case of "leave it to the pros"?

 

On RHD 2003 cars, the two O2 sensor relays should be in the brake booster compartment. They are a pair of relays together toward the center of the windshield. First make sure they are fully seated and have not worked loose. Also try to swap them and see if the fault code changes to Bank 2.

If this is not the problem, it is likely an O2 sensor or connection to an O2 sensor which is bolted into the catalytic converter.

 

It's sounding horribly like a Sensor.



Looks simple from the graphic but there's very little clearance and you have to be careful not to mix up the connectors.

Graham

 

They are also often siezed. I broke three O2 sockets trying to get then off....and I had to remove the cats to get enough leverage. Admittedly they are not always that bad. On my S-type I replaced one without too much of a fight.

 

Thanks guys. You're awesome! I'll check the relays today and see if I can find and get to the sensors as well. Looking at this image:



I take it the sensors are attached to the catalytic converter asseblies (item no 1)? Which one is bank one and which one is two?

Thanks,

 

Bank one is the right side from the perspective of sitting in the driver's seat.

 

I prefer to take the Cats off to change sensors.



If you do this, plan on replacing the fixing studs and nuts as they corrode badly and it's difficult to get a gas tight seal if they are reused.

Graham

 

Thanks guys! Most helpful! It was already dark yesterday when I got home but I tried to investigate a bit more anyway. I tried swapping the relays and visually inspected the connectors etc. All looked fine and the fault code didn't change so I guess it's time for a new sensor. To me it looked like this particular sensor is the most easiest to get to so I will probably try and do it myself...

 

Hmm... A bit confused here. The fault was about Bank 1 HO2S sensor 2. Graham's graphic shows an HO2S sensor located closest to the engine and the other sensor is just called "catalyst monitor". The parts look very similar but they are not the same. I found these parts, both called just Oxygen Sensors:

Oxygen Sensor - C2C25956 | Jaguar S Type, Jaguar XJ - X350 - XJR, Jaguar XK8 - XKR | Jaguar | British Parts UK
Oxygen Sensor - C2S51801 | Jaguar XK8 - XKR, Jaguar X Type | Jaguar | British Parts UK

Which one is sensor 1 and which one is sensor 2? Sorry for my ignorance :z

 

Answering my own question: The complete fault description in JTIS is:

"HO2 Sensor heater control circuit low resistance – bank 1, downstream (1/2)"

So in my case it's this:
Oxygen Sensor - C2C25956 | Jaguar S Type, Jaguar XJ - X350 - XJR, Jaguar XK8 - XKR | Jaguar | British Parts UK

 

Apologies - I missed your Post #9 earlier.

The graphic in my Post #3 shows the sensor numbering.

Graham

 

No worries! Thanks for confirming this!

 

Hi,

Had some time today (before it started to rain again) so I thought I'd try to measure the resistance of the heater elements on both downstream O2 sensors to see if there's any difference. I couldn't get to the actual connectors of the sensors so I thought I'd follow the schematics and try to find easier access points. The other end of the heaters can be easily accessed at pin 5 of the heater relays. The other ends go directly to the engine control module. I didn't dare to disconnect the huge ECM connector though as I wasn't sure if it's safe to do so? Will disconnecting and reconnecting the module mess up the system?

I also managed to drop two of the ECM cover screws under the plastic compartment. Any ideas how to get them out from there? They won't attach to a magnet...

 

The ECM is a programmed module so you can disconnect it without losing the configuration. For absolute safety, I always prefer to disconnect / reconnect modules with the battery disconnected.

I think you'll probably have to remove the ECM to have any chance of recovering the fixing screws from the bottom of the compartment.

Tip for future reference: if there's a gap for anything to fall down, stuff a plastic bag into it before you start dismantling.

Graham

 

I managed to get to the sensor connectors and measure the resistance there. Bank 2 sensor 2 heater showed a healthy 5.6 Ohms while Bank 1 sensor 2 showed about 600 kOhms. Torque app shows 0.6 volts from both sensors when the engine is idling hot so I take it it's not so serious as it's just the heater. Not sure if I will attempt to replace it myself though as it does seem to be in a tricky place...

 

Ok, I ordered a new sensor in the view of at least attempting to replace it myself. Still need to find a 22mm O2 sensor socket (any recommendations?). Does anyone know what is that black branching hose right on top of the downstream sensor in the attached photo? Would be good to get it out of the way...

 

Well... Got the part, got the socket but that's as far I can get. The sensor is seized and won't move one bit. Can't get to it from the top. Can't get her lifted high enough to get proper leverage on the wrench from below. The cats are so rusty I won't even attempt to get them out. Time to hand it over to a capable mechanic. Does anyone know any good indie jag mechanics in London? Could use one for some other bits and bobs too...

Thanks,

 

Just to conclude this thread: I took her to Les Pauls Motors. They changed the sensor for me among a few other things. Haven't got the car back yet but I just received a progress call from them saying changing the sensor got rid of the fault. Whoop de doo

 

Great news, and nice detective work. I remember taking off an O2 sensor from my mothers 2002, and it was frustrating getting it to break loose. Good choice on handing it off to someone with more tools and tricks of the trade.

 

Yeah. I could tell pretty much straight away I wasn't going to get this done in the court yard with the tools I had. The place I took the car to is going to change my front brake discs as well. Again I had the discs but couldn't get the caliper bolts open with my tools. They'll also do transmission fluid and filter change and a full car underseal inlcuding any rust removal etc so she should be purring nicely for a while now

Thank to everyone for helping me getting this sorted