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High NOx fails emissions but no codes - 1997 850 R

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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454cid
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Re: High NOx fails emissions but no codes - 1997 850 R

Post by 454cid »

matthew1 wrote: 26 Dec 2025, 16:40 I have a fear that yes, it is going to end up being the catalytic converter. Colorado is unluckily a CARB state, so this scenario will likely be a bridge too far due to OEM cat prices.


IMG_1682.jpegIMG_1683.jpeg
Does the state require it to be an OEM cat?
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matthew1
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Post by matthew1 »

Can be a certified 3rd party... Magnaflow bolt on is $1300. It looks like OEM is not available at all.
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matthew1
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Post by matthew1 »

It's not the end of the world if it is the cat. I can offer it for sale. Several cities (their counties) do no emissions testing, like Pueblo, Colorado Springs, Durango, Aspen(!), Vail(!), and Telluride(!), so there is a fairly close set (by western US state standards) of potential buyers. GMH offered it to me for nothing, literally, and I gave him a token amount of USD. It would be nice to have for my son who is 16 now, but there's a good chance he's getting a 2009 Cadillac from his grandparents on the other family side. Or I can just tell him he has a free car... until the temp tags expire in mid February. :D :lol: dad humor

He's still on his learner's permit either way until he logs xx hours, and that ain't happening with my VW because it's manual and he's shown 0 interest in learning. I've taken him out 3 times for a few minutes each time (parking lot), and after that I left it up to him to come to me to ask for this and he hasn't. You can lead a horse to water, etc...
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1998 V70, no dash lights on

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ZionXIX
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Post by ZionXIX »

My 96 is exempt from emissions testing in texas since over 25yrs old
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Post by abscate »

Where are your fuel trim sitting on this car? Have you given it a hot run and tried resniffing while hot?

NYS also exempts emissions after 25 years , which is a godsend for keeping an old fleet going. I’ve got an emissions hose crack on Karla. That codes p0440 every 6 months or so, but needs an axle drop to fix.
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matthew1
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Post by matthew1 »

I read a good number of angry posts on Facebook Groups (car enthusiasts) from guys who move here (or are about to) and find out their car can't be registered. 25 years used to be the standard cutoff for emissions and for Antique plates, but that changed ten(?) years ago.

I think emissions policy made a lot of sense in the 1990s when the last 5% of cars on the pollution spectrum were doing 50% or 80% of the pollution... 1970s cars with the first generation emissions gear on them and big, smelly, fun V8s. But as that frame of reference moved up to today, it puts a lot of 1990s cars out of eligibility, and those 1990s cars have 3rd or 4th generation emissions systems on them that even when broken make 1960s cars look like Chernobyl. At what point do you call it Good Enough?

Anyway, I planned to take it in for a test ($25-$30 and ~90 minutes round trip) after O2 sensors, fuel treatment, and vacuum line check (complete, all good). No use going in for a test without changing some variables. I'll give it some fresh premium fuel and give it a good 30 minutes of 5-cylinder symphony before I get in the test line.
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1998 V70, no dash lights on

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Post by abscate »

90 minutes round trip ? Ooofla!

( 2 minute drive , 15 minute walk home)
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Post by matthew1 »

15 minutes drive, 20-50 minutes in line, 15 minute test, etc...
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1998 V70, no dash lights on

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2004 V70 R [gone]

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Post by scot850 »

May the Volvo Gods be watching over you on that test! :D

Neil.
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matthew1
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Post by matthew1 »

My confidence that it's the catalytic converter went from 80% to 95% on Saturday when Steve was here. He brought his advanced scanner and watched the short term fuel trims as I drove. They are normal, 3-4%, so that almost certainly rules out O2 sensors as the NOx cause.
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1998 V70, no dash lights on

1997 850 T5 [gone] w/ MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace

2004 V70 R [gone]

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