I've got '95 Tercel (w/Auto). Check Engine light came on that EGR wasn't working (P0401). Autozone doesn't carry that year's EGR vavle, so had to order from dealership. Replaced the EGR valve, and cleared the code. 2 days later code came right back. Tried clearing it a couple times, keeps coming back (P0401). What's the trick to really clearing this out ? Other than the light car is running fine (and getting 35mpg). Thanks.
Holy Crap!!! You took AutoZone's advice and shelled out for an EGR???!!!!!
P401 is also Low Vacuum!!! I drove my '95 for 3 years with this code, had the EGR tested at a Toyota dealer and it was fully operational. Also replaced both O2 sensors (since I got them at cost +10%...). Checked the vacuum sensor, etc, etc, etc.
Here's what I was experiencing: Sluggish performance and poor gas mileage.
Here's what I did: The ECU is located behind the glove box, with JUST enough room to squeeze your hand in there. There are two plugs; the upper one clears the memory. Pull it for ~30 seconds (with the key OFF!!!), plug it back in and drive for about 3 days with full performance and 45MPG. The light will come on again.
What I was GOING to do before I sold the car was to find the wire that provides +12V constant, and wire it into the wire that only comes on with the key (all the MDT's here, feel free to lambaste me now!!!) This means the computer will ONLY be powered on when the key is in the ON position, and you'll NEVER have a check engine light again! You'll also never be able to read codes again...
Then I got smart before I did that. One by one I removed the Vacuum lines and sprayed them with I Wish I Could Remember What cleaner, and then replaced them. I sold the car about 2 weeks after that, but the light never came on again!
Make sure you use a cleaner that is rubber-hose friendly...
Check for a vacuum leak to the EGR valve, check the EGR position sensor.
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