O2 Sensors
#1
O2 Sensors
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
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
#2
#4
#5
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
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
#6
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.
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.
#7
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
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#8
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
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
#9
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.
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.
#13
Indeed, a strange coincidence. The only common component is the HO2 sensor heater relay.
Graham
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