2000 Volvo V70 XC--Check Engine Light!

[jblackburn]

They do what they were built for pretty well - to get up and run every morning no matter what else is wrong with it. In that aspect, it's never let me down, though some of the EXPENSIVE repairs on other things have definitely got on my nerves.

I guess you could say I tend to drive my cars til the wheels fall off. Looking back, I've put 22,000 miles on mine in a year and a month. Just last April, I had hit 150,000 miles. And it still runs just as good as it did when I bought it.

And with all that, it pretty much sat/was driven by my dad back and forth to work for ~2 months.

While I admit it was nice to have my mom's Honda for those 2 months earlier this year, and not have to do anything but put gas in it (and very little gas at that, compared to my car), it just wasn't as exciting having a car that just...works, and I almost crashed/slid into things in the snow a few times because its traction is downright TERRIBLE in slick conditions where the Volvo shines.

[adk793]

I must say i agree, after my first volvo totaled, my option was to get my moms '03 camry. But i still decided to spend the money and buy a volvo, and at the most part i dont regret it. I must say its a durable car but also very fragile, all the probs come when you start havin some fun with it.

Anyways to get back on the issue of the Check engine P0422 code, what exactly do i do to find the problem. How would i know if it was the O2 sensors or the Cat Conv. Should i take it to my mechanic (volvo only specialist) and see what he thinks--hes an honest guy except he often says this code could mean a lot of things, id need to check it out in detail (then charge me $90 for that). So keep driving wouldnt hurt?

[jblackburn]

Like several said, clear the codes for now and see if they come back. If they come back say, 2 more times or so, then worry more about diagnosing it.

My first matter of troubleshooting would be to hook up a scanner to the OBDII and read the values from the rear O2 sensor at several different engine speeds. You should see the values swinging back and forth - if you get to this step, I can look up a table of values for you; if it seems a bit slow about it or the values are out of range, it would explain the code for the O2 sensor.

Catalytic converters are less of a common failure item, but it does happen every now and then. About the best way to test this is to kick, smack, and shake the bottom of the catalytic converter and listen for something loose inside.

[JRL]

Now if it is the Cat converter, would it damage like the O2 sensors if i let the problem be...and likewise, would bad O2 sensors do something bad to the Cat conv.

Ive done some maintenence/repairs on the car. Is this something i can do myself if i would have to change something?

Absolutely.
If one of these parts is bad, it CAN and WILL damage the other(s) if not taken care of fairly soon, besides you will see performance go way down as will your fuel mileage too!

You can do it yourself.
However, it's a bit hard to get to the bolts and replace a DP (CAT) on the ground, a lift is preferred.
You can buy a used converter from Erie and save bucks, never install used 02 sensors
( http://www.erievovo.com )

[adk793]

looking at the vacuum hose diagram, which hoses do i check. and what do i do with the quick start fluid/carborater cleaner, put it on a towel and wipe down the hoses, or spray it on. What should i watch out for--i was told i can blow the distributor cap/valve. And when i do find a leak, how is it fixed?

[850tech]

Just short quick sprays on the lines and around the TB gasket and Intake manifold gasket with the engine at idle. If there is a leak the engine RPM will slightly raise with the HC (fuel essentially) from the carb cleaner.

NOTE: be careful not to spay the exhaust manifold area as the excess heat could ignite the cleaner.

To check the cat I always start with a scan tool to compare the front O2S readings to the rear. If they mirror each other to within .1-.2 of a volt, I am usually pretty sure the cat is required. That said I don't like to waste my customer's money so I always do a Pre vs Post Cat test with a bench gas analyzer before i condemn the cat

(Pre Cat - Post cat) divided by Pre Cat = efficency in %
This equation is done for HC, CO, and NOx on a 3-way Cat

[adk793]

If you overdo certain fuel additives you could get a code like that because the cat isn't happy.

Would always filling the car with premium grade chevron which has the techron additive be considered overdoing fuel additives--->making the Cat Conv not happy.

Just an update to readers, its been about 3 days and 50+ miles and the light has still not come on. i hope (knock on wood) that it stays this way!

[jblackburn]

Would always filling the car with premium grade chevron which has the techron additive be considered overdoing fuel additives--->making the Cat Conv not happy.

No. That was true of several older cars (my dad actually destroyed his converter by running Premium in his Saab), but these engines/converters are designed to be run on Premium. You are doing the right thing for it.

If the light hasn't come back in ~200 miles, just forget about it for now. Flukes happen. My car had a P1102 stored several months ago for no apparent reason (hadn't turned on the light yet), and no codes have come back since.

[adk793]

unfortunately i write the update soon after my previous response. Its been about 60 miles and the light came back on. Indeed ive been trying to drive gently but its back with the same P0422 code. I had my neighbor use his complex OBDII scan tool check the car. He read the O2 sensors and said they are responding and working correctly. I'm not sure if he compared their readings but he said a bad O2 Sensor would produce a different code. He looked at the engine compartment and says the hoses look fine. He said its most likely my Cat. Converter.He offered me to take the car to a friend of his that has a smog check station and have the car tested to see about the Cat Conv but its most likely it. I really dont have the money for this right now...especialy that i live in california, its gona cost me a shit load of money! Any recommendations?? How soon do i need to get this job done!?

[jblackburn]

Have it tested for sure.

You don't need to replace it until you need to pass emissions again (don't set any environmentalists loose on me).