Hello,

I am having some difficulty with my o2 sensors (upstream).

I will start the story from the beginning. The car was running great mot time came around I took it in and all passed except the emissions, it was due a service so I had that done first.

Co2 was out and lambda.

It just scraped through the mot emissions test after the service they changed filters, oil, spark plugs, cleaned out the throttle body.

It went in for a retest and passed just the lambda was right on the limit but passed.

The car was not running not very well, the problems included misfire, poor performance and hesitation.

I changed both o2 sensors for bosh units, the performance is now back misfire has gone and I have no hesitation.

I checked the ecu again after clearing the faults a few days ago and I found a pending error for both upstream o2 sensors.

I have rechecked all my connections and they are good. Any advice on what could be upsetting them?

Peter

 

Peter,

I've moved your question from UK & Eire Region to XK8/XKR forum. This is the place to post technical questions about your model.

Graham

 

what is the code?

 

Hello Brgjag

Yes the codes I have listed are as this photo they have gone from pending to stored over night it was quite damp this morning could this be a bad earth I am starting to think?

I have a egr valve on order just waiting for it to turn up ( it looks not fun to replace :-().

 

Here's the error code descriptions and list of possible causes from the Jaguar DTC table.

P0405: EGR drive circuits open circuit
1. EGR valve power supply circuit open circuit
2. EGR valve to ECM drive circuit pair – EGR pins 1/3, 4/6 open circuit, high resistance
3. EGR valve failure (stepper motor open circuit)

P1646: ECM HO2S control malfunction – A bank, upstream
1. HO2S heater failure
2. HO2S sensing circuit short circuit to ground or high voltage
3. HO2S sensing circuit open circuit
4. ECM failure

Did you do a 'hard reset' after fitting the new sensors to put the fuel trims back to default?

Looking like a possible dodgy harness connection.

Graham

 

Hello Graham,

If you mean did I disconnect the battery/fuse to the ecu the answer is no but I believe the garage did as this would is the only explanation for the change in its running after the service.

I just cleared the codes from my laptop via the an obd connection.

ok I just need to check bank A is the one on the right hand side if you are sat in the drivers seat?

If this is the case I have checked the harness as far back as I can see for damage and all looks ok.

I do believe you are right with it being a connection issue as the sensor I took out dose work I changed it anyway due to its age.

 

You've got to love Jaguar cylinder numbering and bank identification. It's changed a few times and depends on the model year:

Jaguar Cylinder Numbering.pdf

Even if the harness looks OK, make sure the connectors are seating properly and there's no damage to the pins.

Graham

 

Hi Graham,

To be honest that is what I did before I changed them looking for a quick fix two pins are gold and shiny and two are silver and shiny no corrosion and they are not bent. I am thinking I am going to have to chase this back and check all plugs in the loom until I find the faulty one.

It did strike me as odd that both were giving errors one I could accept but both makes me suspicious. The second only shows up if you code read while driving.

Peter

 

Second one is likely the same problem I have had where if I plug the reader in or leave it in while driving it throws that code- but if I plug it in when the car is off and then turn the car on (not running) it works fine.

As for the other one- have you done the TSB for the EVAP in the driver's side fender? IIRC that resolved my issue. That or a new gas cap.

 

Hello dsnyder,

Thanks for your reply, I am not failure with the acronym TSB what dose it mean I will check it out :-).


Peter

 

"technical service bulletin" It's what the car companies send out when there is a fix for a problem

 

Thank you I will try and find the article and this helped with your egr problem or the o2 sensor?

Peter

 

Peter,

Indeed, a strange coincidence. The only common component is the HO2 sensor heater relay.

Graham

 

Graham,

I should be able to check that the relay is working by taking a reading at the o2 sensor plug what is the normal voltage 12?

Peter

 

Well the weather was not great this weekend so no luck in tracing the fault yet but interestingly I did notice that the "EVAP in the driver's side fender" had been looked at recently so that will need to be inspected due to them making a mess of the clips. Thanks for the tip dsnyder586.

 

Problem solved after much head scratching and the morel of the story is don't skimp on parts!

The bosh units I had bought I managed to get exchanged as the European parts supplier admitted that the units I had been sold were not up to the job and replaced them with the denso units.