Hi Everyone,
I want to thank this forum for the many questions I have had answered by looking though the threads. Unfortunately, there is a long time problem I have not been able to solve and hope someone might have a good answer.

My wonderful 99 XJ8 with 80K miles failed its emission test last spring due to 5 monitors not responding. Since then I have have been dodging the police with an expired sticker but now I can not reregister the Jag as the emission failure blocks new registration. Thus I am looking at about a $500 fine when caught. Being unemployed that would be a killer for us.
Of the 7 monitors, 5 always come up incomplete and I have tried all the drive cycles to reset them many times over.
The ones that do not reset are
Fuel
Comp
Catalyst
Evap
O2 Sensor
The two that reset are
O2 Heater
Misfire

I have cleaned(with electronic cleaner and emery cloth) every connection on the computer and any wire connection I could find as well as all the fuses. Also the grounds I could find.
I had previous problems with the engine which I cleared up by cleaning the MAFS.
Then later, code P1446 came on and I did the connection switch with the O2 sensors and narrowed it down to P1446 and replaced the O2 sensor.
Then came the emission test that would not read the 5 monitors. Then began getting codes P0135(and the CEL), P1446, P1447. I am betting they are upstream problems causing these codes but if the O2 sensors will not reset, how would I get the P1446 and P1447 codes?

Also, the performance goes way down after a clearing of codes but seems to pick right back up which seems to indicate that the monitors are doing their job, but just not able to be read by the scanner.

Also, I considered replacing the MAFS, but looking at the monitors, they can not all be related to the MAFS directly.

I have tried clearing codes by scanner, by disconnecting battery and disconnecting battery & clamping the neg and pos cables together overnight.

Working on my wifes Monte which has BCM problems, I noticed that the same 5 monitors would show up as incomplete after I cleared with the scanner.

My thought is that those 5 monitors are run through one circuit, but I have not been able to figure out which circuit that might be.
Am I on track or does anyone have any ideas?

Next question. The little plastic piece in the rear boot unlocking key assembly broke. Ever notice it is the little plastic piece that always break? Any idea where to get these parts?

Thanks all and have a great day!

 

First, Let me help you with a concept or two- The "monitors" you refer to are actually "OBD test cycles". Google that for a much better explanation than I could give. And, I suppose I understand your reasoning somewhat, But NO, they are not one circuit, except that tehy all relate to the ECU system. What I GUESS is happening is that your car is not going into "closed loop control" (Google that + "engine"). If the engine does not go into closed loop, then it will not even run the tests.

I do not see P1446 or P1447 in any of my "Jaguar reliable" literature for a North America MY 99 XJ8. Is that the right code? Do you know if you have a AJ26 or AJ27 engine? Online I saw references to the Evap circuit.

Now, as to why it is not going into closed loop. My WAG, again GUESS, is that you have the wrong o2 sensor in the position you replaced. To troubleshoot an O2, you need to have a scanner that will trend chart the data so you can see what the O2 is doing over time (or use an oscilloscope). OR, if, in fact, the code is right, then you gotta fix the evap circuit.

 

Thanks Ross,

I did make an error in the codes I posted. They should have read P1646 and P1647.

Thanks for the open loop lesson. It refined what I figured was going on. Guess I need to find a high dollar scanner to use. Any ideas? Anyone know if they are rentable?

Ken

 

My local AutoZone loans tools. I've done it a few times when I knew I would only use the tool once. They normally hold a deposit which you get back when you return the tool.

They have the Actron CP9176L for loan. I'm not sure if it tests what you need, but it's definitely nicer than the scanner I own. It does say it Displays Emission Data, but also says it does NOT Display O2 Monitor Test, so I'm not sure if it will perform the test you need. Maybe someone who knows better can answer that? I would also call other parts stores and see if they might have a loaner scanner that does exactly what you need.

Good luck, and sorry things are tight right now. The economy is definitely hitting us all hard and it bites.

 

Ken:
Ok, its adding up. You have a problem with the lambda (O2) sensor heater circuits. It is either power supply (fuse), wiring, sensors, or ECU. let's hope it;s not the ECU.
With the sensor heater circuit faulted, I am pretty sure there is no way the the drive cycle will complete.

I assume you have a AJ27 engine (Vin later than 853936). First question is where did you get the replacement sensor? Are you SURE it is the correct, wide band sensor. I asume you changed one of the FRONT sensors.

If that is right, then you should check fuse #14 in the underdash (engine management) fuse box. Because there is always some doubt about fuse location changes, check all the fuses.

If you have a voltmeter, you should check the voltage from the purple/blue wire and the purple/ slate wires on the lambdas to ground on a cold start. I would expect to find about 12 volts. Also, look to make sure here are no burns or cuts in the insulation on those wires. Check the white/green ground wires to see that they are intact and grounded.

As to the scanner, the ELM unit with a trending software comes in umder $175.00 or so, BUT for the codes you have, it won't be much help. Wait till times are better.

And good luck.

 

I did the purple to ground on each O2 sensor and it showed only 1-2 volts. I take it these were the wiring leading to the O2 sensors.
I did check fuses and changed out just in case. Showing full voltage through fuse box.
Yes, it was the front O2 sensor I replaced and yes it is a AJ27.
Really can not tell you if the O2 sensor was the right one as I took the parts company's word for it(on-line). But both O2 sensor codes have started to come up.
As far as white/green wire, checking for ground, I did not want to put power to it until I am sure it is the proper method for checking ground. Would I go from battery positive to voltmeter to white/green??
Now comes the rest of the story...
Codes now coming up are
P0327 and goes into restricted performance
P0560
P0135
P1647
P1646
Thought the voltage might be affected by not driving and a low battery, but cleaned posts and ran higher rpm to recharge but no luck.
Cleaned main ground at frame as well.
Had P0327 and DTC come up before but after a short drive the restricted performance would go away.
Any thoughts from the Sage??
Cheers