Yet another P0940

[rajtp]

Guys

 

I'm sorry for posting yet another P0940 problem and I'm probably the 10 millionth victim of this code.

 

Long story short - I had to get my EGR valve cleaned up on my Accord 98 V4 with 153k miles on it. The check engine light went away after doing that and I passed inspection. 3 days later, the light came back on with P0940

 

Question:

Some folks have put in a new 3rd party catalytic converter only to see the code having returned months later. Is it worth spending on a Honda OEM converter to increase my chances of not seeing this code again? If not, can someone recommend me good 3rd party brands and how much do they typically cost (I'm in NYC hence 49 state emissions)

 

Thanks

[Xeryon]

Just ignore the code. Damn ULEV emissions system on that gen was too inflexible to aging vehicle components. The issue is not your O2 sensors or your catalytic convertor it is the engine itself. As the car ages it isn't completing combustion like it used to do so you are getting improper readings and the CEL coming on.

 

The best fix is to buy your own cheap code scanner and just clear the code. Mine used to come on in the summer with the ozone in early June and I could clear it late August and not see it again for months.

[rajtp]

So are you saying it's unlikely the catalytic converter has gone bad and it usually doesn't over the like of an Accord? Or are you saying that the chances of the code coming back even after a converter replcaement are high

 

Also, after the EGR cleanup, my mileage efficiency has dropped from 23 to 19 for the 1st tank fillup and up to 21 for the 2nd tank fillup. My mechanic states it will eventually recover back to old readings. However, shoudln't it have much better mileage immediately after the EGR carbon cleanup?

 

THanks!

[Xeryon]

Fuel efficiencies can change for better or for worse any time you clean or replace parts. Carbon build up in certain areas can change how the engine is operating. A fuel mileage change of only a couple mpg over one tank of fuel is nothing to be worried about. From one tank to another your fuel economy can change 10-20% with each fill up depending on fuel station's pumps, weather, terrain and driving habits.

 

Chances of code returning not long after replacing the converter are high. Although not normal it seems to be a frequent occurrence in 98 Accords when they get to the 150-200k range on the original emissions system. Replacing parts never seems to remedy the problem, just makes it go dormant for a little while. 99-01 Accords didn't seem to have this issue.

[rajtp]

Ok, I cleared the code but it came back after an hour of driving. What strategies can I use in 11 months when I am back due for inspection?

[Xeryon]

Keep an eye on what the weather is like when it will come on immediately or when it will stay off. Also try once or twice using a higher grade of fuel or try a fuel station that uses more or less ethanol %. Mine was very consistent with outside air temps. Once the daily high temp dropped below 80's it would stay off for months.

 

When all else fails you can also look into a seafoam treatment to really clean up the various internal engine parts. A lot of people here swear by it, but I have never used the material myself. http://www.seafoamsales.com/how-to-use-sea-foam-motor-treatment.html