Dear All,


Quick question. My Jag is running rich and scan tool shows both O2 sensors not switching (stuck around 0 V) and fault codes relating to their heater circuit. I checked the fuses under the hood on the right hand side and all ok. I have read that you can try cleaning o2 sensors in petrol - is that a waste of time? I was thinking of just buying two new sensors, but plan to check / clean the wiring connectors first. Anything else I should do /test?
I believe replacement sensors should be 'orientated' by someone with the correct software and I had that done on my last Jag when I replaced the sensors on that over ten years ago. Is the orientation necessary as on other cars we have just fitted a new senor and run fine, passes emissions etc.?


Thanks,


John

 

How old are the sensors? If you don't know, you should just replace them.

Orientation should not be necessary if you replace the sensors one at a time and do not cross plugs.

I believe you have 4 sensors. The downstream ones are the ones that do the heavy lifting, but I would replace all 4...one at a time.

 

Thanks, I have a UK car, so luckily only two sensors, downstream of the down pipe cats. I cant remember if I have replaced the sensors on this car as I have owned it over ten years. I did remove the sensors to repair/ modify the exhaust early last year so maybe they didn't like being disturbed. I did mark them up to avoid mixing them. If they were reading the wrong bank then the fueling would out of control regardless. I will buy the sensors and see how it gets on.

 

All O2 sensors heaters fuse # 14 / 10 amp Right Engine fuse box . According to the wiring guide all S/C engines have 4 sensors . Mine is a N/A engine . Check for corrosion on the Papa Indy 61 connector pin 12 white / green wire as it has a history of going bad . Also check on the 4 wire 4 sensors connectors for corrosion as I found on mine especially the aft connectors .

Upstream Sensors :

Bank 1 Sensor 1: Green wire
Bank 2 Sensor 1: Brown

Downstream Sensors :

Bank1 Sensor 2: Blue
Bank2 Sensor 2: Red

 

Thanks, that is good information. What is the 'papa indy 61' conector? Also my UK supercharged car defiantly only has two sensors.

 

With the only 2 sensors , where are they located with reference to the forward catalytic converter ?

The Papa Indy 1 and 61 connectors are located aft behind right headlights below the blue washer fluid fill cap . There was a TSB addressing the location causing corrosion . For future reference if you need the part number and source I have them but I just cut mine out and spliced the wires with environmental splices .

 

Thanks for taking the time to take pictures, I will check them out. I had some issues a few years ago due to damp/ corrosion in the ecu connectors, so can imagine what can happen. The oxygen sensors on my UK car are in the down pipe section for each bank after the down pipe catalysts, which is unusual, but well before the main underfloor cats. On my car I have removed the down pipe cats as partially blocked and replaced the underfloor cats with two Magnaflow 'sports' units. That made a noticable difference compared to the blocked and rattly originals. This did not seem to have any adverse effects on economy ether possible improvement.

 

Never could determain with the different 2 or 4 Cat configurations which set is the regulating Cats and which set is the comparison for code 420 and 430 efficiency . The different ECU's part numbers in different parts of the world don't make it easier . I don't have much information on the inside of the ECU's but am slowly cracking the code .

 

when replacing all 4 o2 sensors are they are the same one? Or are the 2 upstream and 2 downstream sensors different part numbers? I’ve been trying to look online to buy some but can’t find any straight answers

 

All 4 sensors are exactly alike

The heaters in the sensors can be checked with a meter and they should compare close to the same resistance for all 4

Without the sensors heated up to a certain point the sensor will not read correctly or not at all

3.5 volts is what I have gathered from reading but the 801S doc is different

Bosch # 13789 is a connector ready replacement and to fabricate one as a universal probably could not be done as the wires are galvanized coated and can't wick solder

The wires are brittle, and care must be observed to not twist the wires as are you spin the sensor in

On mine from the previous owner the wires were broken and sticking out of the insulation from poor craftmanship

The hex is a 17 mm and the copper crush washer is smaller then that of the X300 spark plug , but can be obtained if missing from a cheap 12 MM spark plug