Justin Hi Paul, If the Cat is restricted with Carbon, that carbon will prevent the light off temperature from being realized, if the carbon can be cleaned the Catalyst may return to the light of stage. Is the work being done at a shop with a Guarantee? P0421 is probably the Cat, I had to replace mine too, but it shouldn't cause the engine to misfire. ? I saw yours problem with Po420 refers to cataliytic con. I have a scan tool, and I can see live stats, but I don't know what the two o2 sensors should be at. I,have a 2003 jeep liberty.
I'm going to the dealership tomorrow to have them check the code and see what happens!!! To the cause of the noise, has anyone evaluated any of the seals in the front rotating masses for dryness and noise? If the light goes away, woo hoo it's fixed. They reset the code with the hand-held computer and sold it to me. Scanned it, found a random misfire. I noticed that instead of max 100 i had like 350 on idle speed which is way off limits. Larry Justin, thanks for sharing your expertise on this site. Do you have any suggestions or ideas, or anything else to try in reference to my situation. Took it in last week for check engine and was told that it was the Sparkplugs.
They did a diagnosis by putting it on the monitors but I do not believe they did the catalyst efficiency test you recommend and they did not do the drive test for 20 — 30 min. Had 3 diagnostics done showing po420 code which means basically bad catylitic converter. Thanks to the Internet one forum guy was like intake leak, check your manifold for cracks and or bad gasket, but I did and I did not appear to have a leak, guy responded do it anyways I'll put money on it not really gonna happen right? I need to know what I should do first. Don't accidentally take the temperature of heat shields, pipe only. After the converter was changed, I drove it really hard to see if the problem was fixed.
To fix your particular P0420 issue I encourage you to make sure the engine is performing perfectly, sensors and all before spending the money to replace the catalytic converter. I noticed I am getting high long fuel trim around 23% sometimes 24%. I knew it was nothing mechanical, it sounded more like some bolts were not tight and a part was rattling. Two days later it was back on. Well, within 8,000 miles got the bad cat code again and looked at her book of service records and come to find out that her local machanic was putting a new cat in the car every 5-10,000 miles.
The only way to cut down on this is to put more precious metal in the Catalyst which would greatly raise the price. I have spent the last hour or so reading all the posts. My 2004 Legacy keeps showing a P0420 code. In the afternoon I got in it and the idling issue was back and car had same issue where I could barely get any power and car is bucking, check engine light flashing again. I have read that the leaking head gaskets and the additives they used to put in the oils cause the inside of the cats to deteriorate. So they cleared the code and said it possibly could come back again.
Ignored P0420 code all Winter because it came and went, every time it got cold. Rather, all these codes simply mean the converter is running below the efficiency it is expected for, or it is running below threshold. Well one thing i learned about the obd 2 system is that it will point you in the right direction, the po 420 code is for the left bank or side of the motor looking from the drivers seat in a rear wheel drive car,the computer is telling you through the o2 sensor on the left bank or left side of the motor that their is a problem in that area, in my case it was an oil seal on the left bank or side,the exaust valve on number 3 on my 3. I took it to autozone to have them read the code it still gives P0420. Justin Hi Justin, Have a 2008 Outback 2. Justin Hi Justin, I have a 2004 Legacy with the 420 code. Mechanic said the cat is working fine on it.
I suspect they did not do much more than that. This holds especially true when considering that the catalytic converters are usually the most expensive part of the whole exhaust system. Is this indicating it is the cat conv at engine end that is reading below threshold. Since the catalytic converter is not designed to wear out, its failure is normally associated with some contributing malfunction. Drove around for ten minutes and it came back on. But I will save that for another article. On to the good news.
Should I just bite the bullet and have it replaced? What is the configuration of the extender. Mine are pointing that way too. Things have been fine with alternator since then. Check for Exhaust leak first, specialy close to O2 sensors. If the cat was clogged you will most likely have misfire p0300 dtc's and a insuffient activity code for bank 1 sensor 2. This time I drive it all the way into the mechanic since I know it's a misfire.
I only wish you were in New England instead of Seattle. Replacing the up-stream oxygen sensor has solved my particular P0420 check engine code. Any suggestions would be great. Rember your cat converter must be a calif emissions approved cat or your light and smog will not pass. I did the o2 sensor myself so I'm wondering if its likely that it means I just need to re-wire it or if it's really something else going wrong.
Any direction would be greatly appreciated. Its the single most ignored code, and one the the most challenging to accurately diagnose. Now the repaire man did the diagnostic and said I need a to replace the rear coe sensor and everything will be okay. Thank you for your time. Cleared code and light came back on in 30 miles.