2015 XC70 T6 Code P0420

[MsRed]

Good afternoon,

Ugh
Nasty P420 code came up about six weeks ago on my XC 70 with 176,000 miles (good condition, new tires, breaks, doesn't use oil - great interior, only has a few exterior scratches). I moved, and my regular mechanic is now more than an hour's drive so I took my car to a well rated local "muffler shop" who said they found no exhaust leaks, O2 sensors tested fine, and advised I needed the catalytic converter replaced. Quoted me $2,200. Later, they called me to say they weren't equipped to do the work due to make/model.

Prior to the P420 code, I had always used premium gas with my Volvos until about two months ago when I began alternating premium with regular gas because of the cost increases. Between the code coming up and taking it to the local shop, my somewhat car savvy BF (Ford lover) claimed he fixed same issue on a car he previously owned with cleaners so I let him try it. The code went away, but it came back within a week after a few days.

So, now I'm planning on dropping it off at my regular mechanic's shop. My regular Volvo mechanic was former shop foreman at Volvo dealership before owning his independent Volvo shop. I've known him 20+ years and we're friends . . . Because we're friends (and he knows I have a 2003 V40 as back up) it takes a long time to get my car back.

Anyhoo, my question is does $3,000 sound reasonable? And is there anything else I should ask him about before dumping $$$.

I had only planned on keeping the car another year or so . . . guess I'll have to keep it longer now.

Thanks in advance <3
Brenda

[pgill]

Brenda

I saw your reply to the other thread (thanks for that)

I am going to reply here on this thread.

The code is for the oxygen storage capacity of the catalytic converter. The important thing to remember is how the engine computer knows if the storage capacity is adequate.

The engine computer adjusts the mixture to make it slightly lean and then slightly rich. When it does this it expects good ignition and good fuel spray pattern.

With this in mind I suggest the following

1. Replace the spark plugs with actual Volvo plugs or the same plug without the Volvo box from DENSO. The plugs are Iridium TT.

2. Get a fuel injection cleaner that contains PEA. For my Mercedes 3.0 twin turbo I use Red Line 60103 SI-1 Complete Fuel System Cleaner but there are other options that should work as well

3. Clean the MAF sensor

4. Replace the PCV assembly or at least the diaphragm

5. Replace the Thermostat for the engine

6. Replace the intake manifold gaskets

I would do all of these before replacing the catalytic converter.

I listed the items in the order that I would fix them

Good luck

Paul

[MsRed]

Thanks, Paul! These are all great suggestions. I'll go over my receipts/invoices for what my mechanic has done and talk with him. My background is in accounting and legal. We have a bit of a barter thing going and he sometimes doesn't list everything. I'll write back!

Brenda

[Vova585]

1. Totally agree with use of injector/valve cleaner additive.
2. Switch back to high quality gasoline(cheaper than any of the repairs by much!!!) I prefer nonethanol gas.
3. Get yourself a cheap code reader/eraser(they are like $40) and clear the codes.
4. Take a car for a highway drive and give it a good "Italian tune up"(it might help to clean catalytic converter if your base driving is city stop/go).
5. Note how long it takes until the code is back. If it is once every 400-500 miles. Ignore, erase code, drive.
6. Get alternative opinion from your volvo mechanic friend. Some more advanced shops have a specific software that can accurately pinpoint issue source. Meaning catalytic converter or issues prior to it.
7. Another alternative is to assume that you will be using this car "only for offroad purposes" and in that instance I would recommend to i stall nonfuller device(extension screw in spacer between catalytic and rear O2 sensor). Your BF likely can do that since many shops would site EPA rules. Part is only about $30 and helps eliminate the code..