1996 850 GLT OXS readiness on/off, inspection, intermittent CEL zionx thread from WDYDTYVT diary

Post by **abscate** » 15 Dec 2018, 18:50

Original post byZionxIX

Morning all, I am trying to join the legions of legally inspected cars. There is a specific post I cant seem to find that mentioned an alternative drive cycle like a 20 minute highway drive that would clear the readiness monitors. I constantly monitor my emissions readiness with the torque pro app. I took a long drive yesterday (300 miles) and about 20 minutes or so into my drive the catalyst monitor changed to "ready". I've been trying to clear that one for months but I live currently in a small town with no highways. I was ecstatic that all monitors were finally complete. When I got to my destination I of course shut off the vehicle and drove it again an hour later only to see the catalyst monitor as "not ready" again. Does the catalyst monitor reset at every drive? My mechanic friend doing the inspection advised me to come by the shop if it clears again and just leave it idling so the monitor doesn't clear again. Anyway, I would much rather do the longer trip than all of the 2 min and 6 min and stopping to idle drive cycles at specific rpm.

(Couple of answers to insert here)

It does not reset on each drive so my guess is you lost voltage to one or more OXS sensors.

Another explanation is your reader might not be compatible with the Car and your readings aren't reliable.

I would idle it to get the passing grade then deal with it after

Post by **ZionXIX** » 15 Dec 2018, 21:23

So driving around today, on each trip had the usual mixture of city and highway travel. The catalyst code is completing on each drive after about 15 minutes. I'm gonna stick to the plan of idling for the inspection. I did experience an oddity while out today. I was idling after filling up at the gas station and randomly the check engine light came on, the rpms jumped to 3000 and my O2 monitor changed to incomplete. The CEL light immediately went away and the rpms returned to normal. The O2 monitor changed to ready after a few minutes. I'm starting to wonder if oxygen sensors should be next on my list.

Post by **abscate** » 16 Dec 2018, 02:06

No, but an electrical fault that is breaking voltage to the ECU should be.

The two starting points for diagnosis testing are:

Electrical part of ignition switch

Main relay ( tucked under the lip of radiator cover I believe)

But....first, look at all the battery and ground connections , remove and clean until the are shiny, replace clamps firmly, check voltage drop to Main power fuse box with voltmeter. If the battery is over5 years old, consider a replacement if bread isn't too thin.

I'll break this diagnostic thread out of the diary here

Post by **ZionXIX** » 18 Dec 2018, 15:45

Took a 20min drive while keeping an eye on the emissions monitor status. By the time I reached the shop they were all set to "ready" and I left the car idling while waiting for my inspection. I passed so I'm happy. I wonder if other drivers are having a similar problem where some if the codes reset when the vehicle is shut off. One thing to try is leave vehicle idling when you arrive at the inspection place instead if turning it off and going in. Just a thought.

Post by **misha** » 18 Dec 2018, 16:13

Those apps are not reliable at all.
You will need a code reader with live data...VOL-FCR(newer version) have live data option.

Post by **ZionXIX** » 18 Dec 2018, 16:45

misha wrote: ↑18 Dec 2018, 16:13 Those apps are not reliable at all.
You will need a code reader with live data...VOL-FCR(newer version) have live data option.

Worked flawlessly for me. All readiness monitors complete, watched the service guy run the inspection computer. All passed. Torque pro app has never let me down with the bafx bluetooth reader.

Post by **ZionXIX** » 02 Jul 2019, 08:40

Revisiting this thread a bit. I'm still able to get my emissions codes to set after a 15min drive with variable driving condition but I can't get the ecu to remember the readiness. Everytime I start the car the codes are incomplete. It was suggested to me that my grounds may need cleaning and that maybe the ecu loses power when the car is off. I did that yesterday, cleaning 3 ground straps I found 9n the engine bay and the 2 ground under the rear seats. Also the battery and individual battery cables. ECU still not remembering readiness status. Thoughts? I guess I'll have to tell my inspection guy not to turn off the car again.

Post by **ZionXIX** » 02 Jul 2019, 10:08

So an interesting observation. I had a 15min drive beginning with several miles of 35mph city driving with stop lights spaced every mile or so. Then highway driving ranging from 20mph traffic to 80mph road rage driving. All codes including catalyst co.pleted on the drive. I drove with AC off in sport mode and did do anything special. Drive like a I normally do.

On the way back the codes started incomplete. I drove the exact reverse course with AC on full blast in sport mode. Catalyst cleared before I reached my destination. Evap always clears once I park and idle for a few seconds.

I know I've been told to turn AC off for emissions codes to properly set but I don't believe that anymore. I think the key is don't turn off the vehicle when you get to the shop for inspection.

Post by **abscate** » 02 Jul 2019, 10:19

I know I've been told to turn AC off for emissions codes to properly set but I don't believe that anymore. I think the key is don't turn off the vehicle when you get to the shop for inspection.

That part is accurate, the EVAP readiness cycle is cancelled if the AC compressor is on, so it won't go ready with AC on

Post by **ZionXIX** » 02 Jul 2019, 10:47

abscate wrote: ↑02 Jul 2019, 10:19
I know I've been told to turn AC off for emissions codes to properly set but I don't believe that anymore. I think the key is don't turn off the vehicle when you get to the shop for inspection.
That part is accurate, the EVAP readiness cycle is cancelled if the AC compressor is on, so it won't go ready with AC on

My car must not have gotten the memo. I watched it turn from incomplete to complete with the AC full blast the entire drive. Strange.