96 Celica GT: Fixing a P0401 ERG Flow Error Code

[zumajim]

I have a '96 Celica GT 2.2 Liter with 172K miles. My OBD-II reader tells me that the ERG valve flow is insufficient. Having read up on the subject on this forum and YouTube, it seems the usual culprit is carbon clogging. I took off the EGR valve and found it to be very clean. It's definitely not clogged, nor are any of the hoses connecting to it. I might replace the EGR, except that there is also an EGR modulator valve next to it that may also be bad. Has anyone simply replaced the modulator and gotten the all-clear on the reader? It would be nice if the $47 modulator (held in by a simple bracket) was the issue and not the $149 EGR valve (a real pain to remove/replace.)

What would you do?

Thanks,

James

[zumajim]

Sorry, I meant "EGR" (Exhaust Gas Recirculation) not "ERG" in the title and body of the post.

[zumajim]

So that's $150 wasted. Next I will replace the ERG valve modulator. This is a $50 part in stock at the local O'Reilly's Auto Parts. I'll report back.

And if this doesn't clear the error code, I'm resigned to the local Toyota dealer.

[zumajim]

OK, so I replaced the EGR modulator yesterday at a cost of $53.00. Still no joy. Check engine light stays off for ~20 miles and pops right back on again. I'm now $200 bucks poorer. There are other elements to the EGR system including a bewildering number of probes and actuators. Anyone know what to look at next? I said I was gonna go to a dealer at this point, but still think I can pull this off. One last try, if I just know what to look at.

[zumajim]

Since I'm the only one keeping this thread alive, I just thought I'd add that I had the Vacuum Switching Valve (VSV) replaced yesterday (part cost: $35, labor: $95 -- couldn't reach it myself so took it to the local mechanic/bandit). Check Engine light stayed off for a whole 35 miles this time! Still throwing the P0401 error. Officially giving up at this point.