I had the battery changed 6 months ago so when my car was rejected due to oxygen sensors and cat converter not being ready, mechanic and Volvo both told me to drive it on highway. I drove it on the highway in addition to following a sequence I found. A few days later I brought it to my mechanic to see if everything was “ready” and everything said “not ready”. He said something must be wrong w the computer and Volvo would need to handle it. I called Volvo who again said to keep driving.
Yesterday I went out on the highway and drove again along with doing that drive sequence. I then drove right to emissions testing where it was rejected AGAIN. This time the evap system was not ready in addition to the oxygen sensors and cat converter. Is it normal to see them ready and then switch to not ready or is there an issue with my computer?
I called another mechanic who said he could drive it until everything was ready and then take it to the emissions to pass the test. If he can’t get everything to say “ready” my only choice is to go to Volvo. Any suggestions? My car only has 20K miles on it. I live in the city so only do short drives. I’ve never had an issue since purchasing the car new in 2007. Any help would be greatly appreciated. Thank you.

 

A 15 year old car with 20,000 miles? Wow.

I think the first thing I'd do is to purchase a cheap OBD reader. That'll save you lots of time, since it'll let you check the readiness indicators yourself.

You mechanic seems to think that the car just needs some miles (road miles) and he could easily be right. The catalytic converter works by coming up to a (very high) temperature, and it could be that lots of short trips don't get it there, and it's suffering from condensation and/or the engine spending all its time not yet warmed up (during which time it runs richer, potentially allowing more build-up in the catalytic converter).

If you want to do the easiest possible DIY to see if you can get it through inspection, I'd try a bottle of "cat cleaner" in the fuel, and a road trip (steady state highway cruising), with some full throttle operation (which dramatically increases the temperature inside the catalytic converter). And if you have a $10-20 OBD reader, you will know if that works (or not).

If it doesn't, I'd suspect the "downstream" (post-catalytic converter) O2 sensor, which aren't that expensive or hard to change.

 

To be clear, it’s normal to be “ready” and a few days later not be “ready”? My mechanic thought there was something wrong with the computer due to everything going back to “not ready”. If I drive with a reader until everything is ready, my fear is that it will go back to “not ready” when I turn my engine off.

I’m not knowledgeable when it comes to cars. I’m happy to go to autozone and buy an OBD reader. Is there a certain one I should look for or will any reader work? I don’t want to screw up anything so if there’s one for dummies that would be ideal. I really appreciate your prompt response.

 

When did your statuses switch from ready to not ready? I see you mention it in your post but not when it happened. If it was after the battery change, completely normal.

+1 on having a reader to check the monitors yourself. I keep a $15 reader, that connects to my phone, in my car for emergencies and it has been a great tool to have. I got it on amazon. As far as I know, any obd2 reader will be able to scan the readiness monitors.

 

(kind of a close-out of a decent scanner since the new one is now available, I think).

Many times (more than I like to admit) I just drive around in a car that has issues, waiting for the readiness indicators to click over to "ready", then head straight to the DMV inspection station. It's likely that once they DO "go green" you'll be OK heading over within a day or two (but of course, check the status before making the drive over).

One detail many people don't understand is that resetting error codes (like the ones that turn on the check engine light) resets all your readiness indicators to "not ready". Disconnecting the battery may (and apparently did) do the same thing.

 

It switched from all but 2 ready to all not ready within a week. This is all months after the battery was changed. Then I drove it for about 45 mins a week after that and cat, oxygen sensors and evap systems weren’t ready. I’m trying to figure out if it’s normal for all but oxygen sensors and cat to go from being ready one day, all not ready the next day and all but 3 ready a week later- this is months after a battery change. I assumed once they were “ready” they would remain “ready”. No one can answer this for me.

 

I understand that replacing the battery would cause everything to reset. However, months later I was not aware that the codes could go from ready to not ready on a daily basis. I’ve never had the CEL go on. Maybe my mechanic is correct and there’s a problem with the computer?
Thank you for the link to the scanner.

 

I suppose it is possible that the computer has some sort of glitch - presumably one that causes a reset of some sort (the same type that resets all your readiness indicators).

Or you have a flaky catalytic converter and/or O2 sensor, and a separate problem with the evap system (easiest one to check is the gas cap - if the O-ring that seals it isn't in good shape, or if the internal "valve" has failed, you get a separate failure).

If the readiness indicators ALL flip to not ready unprovoked, I would suspect that computer.

If it was my car, I'd probably just keep the OBD reader handy and be ready to head to the DMV inspection the microsecond you get enough "readies" to pass (IIRC, most states allow two "not ready", some only one).

 

This is exactly what my mechanic said. Since all of the readiness indicators flipped to not ready, he said there was something wrong with the computer. I drove it after he said that for about an hour and all but 3 switched to ready. Something isn’t right. We can only have one “not ready” to pass and thus far the O2 sensors and cat refuse to switch to ready. I did fill my car up with gas before driving so maybe that caused the evap system to not switch to ready.

I could drive for hours and they might not switch to ready. This doesn’t make me feel very safe if there is indeed something wrong. Thank you for your help.

 

If it's any consolation, I can't think of any driveability / safety issues relating to a not ready indicator (barring other issues that will set off the check engine light). And yes, driving for hours might be just the trick to get the car through inspection, even if it soon after reverts to "not ready".

 

I’m not capable of driving it for hours. The testing place is about 30 min away depending on traffic. Is the reader you linked easy to see/read when driving? Maybe I’ll give it one more try.

 

It should be easy enough. You'll want to get used to how to bring up the readiness screen so you don't have to fiddle with it while driving.

 

I would prefer if it was a color screen so I could see when each item is “ready” while driving but will purchase this one because you know much more than I do

 

LOL... thanks for the confidence, but by all means, feel free to find one that better suits your needs. My suggestion was based on a very quick search - there could be better options out there.

 

The o2 and cat readiness monitors are always the last ones to flip to ready. I think habbyguy mentioned before it needs to reach a certain temp, have a rest period before cycling again to that high temp, etc.

 

We are getting snow so I will try again next week. I need to order an obd scanner so I’m not driving blind.

 

you also may want to read up on your states emissions laws - you may be able to apply for a waiver or at least entitled to a retest with a grace period.

 

thank you. I don’t think IL has a waiver but some more time might be an option.

 

I apologize for all of the questions and greatly appreciate your help. After reading the .pdf manual for the OBD reader, I’m confused as to if it updates as I drive or if I have to wait until I’m done to check it. I also saw that I need to turn the engine off before disconnecting it. I plan to drive and hopefully go right to emissions so would need a reader I can look at that updates in real time.

 

I always go up one menu level, and then back to readiness check on my own OBD reader, just to make sure that I'm not looking at "old data". I've never had an issue disconnecting the OBD reader without turning the engine off, though I guess I probably do it that way just because it would be the normal sequence (do whatever I'm doing with the OBD reader, shut the engine off and unplug and store the OBD reader).