EGR strikes again...

[castmaster]

Actually my check-engine was popping for almost a year now with EGR codes... But knowing what the trouble is, how hard it is to find the malfunctioning component and associated costs I never felt like spending time and cash on it... the only thing which bothers me is the check-engine lights.. Anyways, we had some quite cold periods this winter and i've noticed that whenever it was hitting below -10 deg C, check-engine would go away... I was wondering if that could indicate where to look? What to replace? Got to fix it anyways...

[Luckynumber5]

Under a certain temperature the EGR is supposed to shut off. You need to get the CEL scanned and post up what the codes are, you can get it scanned free at most auto stores.

[castmaster]

Correct, I went through Toyota's TSB-s and found out that EGR/EVAP monitor doesn't work below -10deg C

As far as CEL codes go, here is what I have:

P0401
After the engine is warmed up, the intake manifold absolute pressure is larger than the value calculated by the ECM while the EGR system is ON (2 trip detection logic).

Possible Problems
EGR valve stuck closed <= Most common Clean EGR valve
EGR Vacuum Switching Valve (VSV)
Open or short in VSV circuit for EGR
EGR valve position sensor open or short circuit
Vacuum or EGR hose disconnected
EGR valve position sensor
Manifold absolute pressure sensor malfunction <=See P0105 above for testing MAP sensor
ECM

[toyomoho]

Sometimes the EGR valve gets stuck or the tube running to it becomes plugged. The valve and tube can be cleaned. Check the link below for the service info on this car.

http://oregonstate.edu/~tongt/camry