Catalytic Converter vs EGR valve…


Hello all, I have a 2001 Toyota Camry LE and have noticed a significant decline in gas mileage over the past 3-6 months (19-23mpg now vs 25-30mpg prior). The car runs smoothly in idle and in general, and I haven’t noticed any problems in street or highway driving. Probably unrelated, but the valve gasket has a small oil leak, as does the radiator, and the right rear wheel bearing will need to be replaced soon. The check engine light came on today. I took it in for diagnostics and they said there were error codes for both the EGR valve and the catalytic converter.


Any idea which is the more likely culprit based on the description? Anything I can do on my own to figure it out? Any other solutions to the problem I should know about? I am basically broke so I don’t really know what to do here and I don’t want to get bamboozled by a mechanic who just wants to replace everything at once. As I said, the car seems to be running fine other than a decrease in gas mileage.



Thanks!
-Jon

 

Do you have the code numbers? They are very specific as to the problem area.

Was the check light on, or blinking?

California or Federal exhaust emissions? Look on the under side of hood for a sticker stating something to the affect of FEDERAL or CALIF. Makes a difference on converter setup.

EGR has several codes.

Converter can plug up, the result is decreased MPG.

How mechanically inclined are you?

The EGR can be a DIY, the converter more work and $$.

Check your library as to if they have something like a Haynes shop manual to check out. Some libraries have Toyota shop manuals in reference. Or buy a Haynes manual, cost around $20. The internet many have used ones cheaper.

If broke, try to do your own repairs. Harbor Freight has OK tools at cheap prices.

Try to determine where the radiator is leaking. The upper and lower radiator tanks are plastic and can crack. The crack(s) can get larger over time, resulting in very large leak.

 

First of all, thank you very much for your help and your detailed response. Here is an update. I bought a third party radiator for less than $100 and did the job myself. Just in time too, as it started leaking very bad on the way home from the parts store.

As for the cat, I didn't see any stickers on the underside of the hood regarding the emissions type(Fed or Cal). I will be driving across the country next week and moving to a rural area where their is no emissions testing. I'm mostly concerned about whether it is just functioning poorly (in which case I could wait until I had more money to replace it) vs. if it was clogged I would need to replace it sooner (possibly before my long drive).

To answer your questions: The codes are p0401 for the EGR and p0420 for the cat. The check engine light comes on stays on after a few drives.

I bought an OEM VSV and am having a trusted local shop install it for me and hoping that it will solve the EGR problem and the P0401 code will go away. Any chance that this will solve the P0420 code too? (ie. any chance that super-rich exhaust due to faulty VSV could trigger the 420 code due to the cat not being able to filter it adequately?) Also, if the P0420 code continues to pop up is there any way I could tell whether or not the cat was just inefficient vs being clogged up? I'm hoping to not have to replace the cat until I have more money. I've heard if it is clogged it may get extremely hot so I shouldn't park over tall/dry grass. Duly noted.

Any further input you have is much appreciated.

Thanks,

Jon

 

Converter operation is not checked by rich or lean exhaust condition. There are 02 sensors on the intake and exhaust sides of converter. The engine computer compares the signals of the two sensors. Based on programming and how the converter works to change the 02 signal of exhaust, the computer will trigger code if the 02 signals are not as they should be.

As such the P0420 is most likely a bad converter. If concerned about plugging have the mechanic use an vacuum gauge to check for excess back pressure caused by a plugged exhaust system.

The most common symptom of a plugged converter is lack of engine performance on hwy. A bad converter does not necessarily mean it is plugged.