HI
My US 1995 Jag XJS 4.0 is throwing two codes: P1185, P1186 Oxygen sensor heater open and short

My Questions:
Are there two types of "O2 Sensors" (Heated and Non Heated)?
Assuming there is only one type of OS2 sensors are there a total of 4 sensors or 2?
Do the new sensors need to be "oriented"/"paired"/"introduced" to the ECU or can they be removed and replaced?

 

I just posted the ELECTRICAL GUIDE for the 1995/96 XJS 4.0

https://www.jaguarforums.com/forum/x...rt-2-a-265975/

 

There are 4 identical oxygen sensors for your US AJ16 engined XJS.

As long as you are careful or replace each oxygen sensor one at a time, there is no need for any orientation to be performed. The orientation is there to ensure each sensor is connected to the correct plug. Something that can really only be done if you remove more than one sensor at a time.

Bosch 13789 is what I have used in the past, but some people don't like Bosch, so they use either Denso (OEM) or NTK. I have found that all brands have an NTK stamp on them. (I haven't checked out the Walker brand)

Oxygen sensors aren't lifetime parts and do wear out. I would recommend replacing all four at this time, since they're likely original to the car.

 

It is critically important on the AJ16 engine that you get Titania chemistry O2 sensors and NOT the voltage generating Zirconia types. Titaina types create variable resistance, not a variable voltage. Use ONLY Titania type sensors.

Yes the sensors are heated (so that they respond sooner in the startup cycle). The USA is an emissions country and the cars here have O2 sensors for both pre and post cats (this lets the computer monitor if the cats are working or not), though many European models only had 2 sensors. It's the pre-Cat sensors that do the majority of fuel trim. The post cat sensors mostly do the monitoring of the cats.

~Paul K.

 

This is FALSE. It is the downstream sensors that directs the ECU to trim fueling. The upstreams are the check. I know that's an unusual configuration, but that's how they work on these cars.

https://www.jaguarforums.com/forum/x...ensors-173577/

 

Vee,
Thank you for your response. Apologies for the late acknowledgement, I was under the impression that I would receive a notification when there was activity on my question. I'll check my profile settings

A quick clarification please
1. Disconnect the battery
2. Replace each sensor, one at a time. They are identical, so buy a total of 4.
3, Reconnect the battery

Does "no need or orientation" mean no need for special work with the comptuer. DO I need to clear the codes? Simply start the engine?

 

Have you carefully checked the heated O2 sensor fuse?
Should be in the boot on the right side.

 

I wouldn't even bother to disconnect the battery, but I like your "better safe than sorry" approach! (certainly wouldn't hurt)

No need to reorient the sensors, as long as you don't mix any of them up when you install them. Installing them one at a time would eliminate the risk, therefore eliminate the need to reorient anything.

Just start the car.

The codes should go away. I don't believe these are the kinds of codes that remain on until "x" number of restarts has occurred. If you were able to pull the codes, you should be able to clear them with the same device.

 

I am giving an update on my 95 Jaguar XJS, 4.0 Liter O2 sensor issue with the hope that I help someone else.

Firstly, I learned that 4.0 Liter is OBDII compliant. I used a OBD Scanner that I bought 15 years ago and it confirmed I had a O2 Sensor issue. This scanner has neve failed me, the one I used is a CRAFTSMAN 87702. You can probably get them for dirt cheap

The 4.0 Liter has two O2 sensors in the exhaust manifold (UPSTREAM) and supposedly 2 more after the catalytic convertor (DOWNSTREAM). I replaced the UPSTREAM ones. They are easier to get to than Sparkplugs!

I used the scanner and cleared the codes
Turned the car off, kept the battery connected
VERY CAREFULLY, I unplugged one harness, followed the wire to the O2 sensor, removed, replaced and plugged back in
VERY CAREFULLY, I unplugged the other harness, followed the wire to the O2 sensor, removed, replaced and plugged back in
Started the car, NO CHECK ENGINE LIGHT.

Drove the car, Parked it. Drove it again a few days later. Not seeing any lights. I swear it runs quieter.

I've seen lots of O2 threads on this forum. I hope this helps the people with 4.0 Liter motors

My mechanic quoted me $839 parts and labor to replace these sensors. I did it for under $300 (they are expensive buggers)

 

Vee,
Please see my update to this issue. THANK YOU for the assistance. I procrastinated for months and finally decided to "face the music". May it took 45 minutes to do the whole job