Please Help! 1998 Camry 2.2 P0401 - can't figure out - Toyota Nation Forum : Toyota Car and Truck Forums

kwg2005 · 04-11-2011, 12:12 PM

Hi. I got this camry that keeps getting the P0401. I took the EGR valve off and it's ports are clean and i verified that the valve works by sucking on a hose and watching it work. I checked all of the vacuum hoses. i checked the vsv and it works. I found one thing that is strange. The two ports on the throttle body that supply the vacuum to run the egr system do not provide a vacuum. Is there some sort of switch or something within the throttle body that engages these, or are they supposed to always be providing a vacuum?

I saw a post from tech1984 (i would send him a private message but don't know how. This is his reply to someone elses p0401 problem:
"Another vote for the EGR VSV, They can only go clicky-clicky so many times in those thousands of miles driven. (9 out of 10 fixes my customers)
Or, they can get contaminated particles from the throttle body. Check those 2 ports on the TB."

what am i supposed to be checking for? a constant vacuum from those two ports on the TB? and what if there is no vacuum? thanks a bunch, any advice is greatly appreciated.

-Ken

dcbc991 · 04-11-2011, 12:53 PM

Sounds awfully like the EGR switch on the back of the block. It's a real pain to get to it. I think I had to remove the passenger front wheel before I could reach it. One of the lines coming off your EGR valve runs back and connects to this switch along with a wiring harness , IRCC. Cheap to buy, but a pain to switch out. Once you replace it, you should be good to go.

Hank, Northern IL

kwg2005 · 04-11-2011, 04:52 PM

thanks for your reply. The switch you're talking about is the VSV, and i already cheked it. I also relocated it to the firewall for better accessibility. I am really wondering why the throttle body isn't pulling a vacuum on the two ports.

kwg2005 · 04-11-2011, 07:59 PM

anyone? any ideas?

71Corolla · 04-11-2011, 08:39 PM

The VSV for EGR can test just fine, but fail intermittently as you drive. I suggest you replace it with a new one.

***fenixus*** · 04-11-2011, 08:45 PM

even worse, it can pass testing off car and still be doing dirty tricks on car. sometimes the wiring harness ground on back of engine gets dirty and makes that VSV unable to complete circuit ... had this problem on 5s-fe even after replacing VSV with a new one (sold the old one on ebay, was good). cleaning the ground point fixed the "electrical" problem with VSV.

Quote:

Originally Posted by 71Corolla

The VSV for EGR can test just fine, but fail intermittently as you drive. I suggest you replace it with a new one.

71Corolla · 04-11-2011, 08:48 PM

Good to know

I've repaired this problem twice, the first time I went through all the testing procedures and found nothing wrong. Replaced the VSV and the problem never came back. Second time, I just replaced the VSV, solved the problem. I also did clean the EGR systems at the same time.

kwg2005 · 04-15-2011, 06:00 PM

thanks for the input everyone. on my prior post i noted that there was no vacuum coming from the ports on the throttle body. I based this on using my finger. I actually put a vacuum gauge on the TB ports and it is indeed pulling a vacuum, a good strong one too. I did replace the VSV in case the problem was intermittant, but the light popped back on. I think the grounding wires are fine since i just put them on the car after changing the head gasket. One other thing I noticed is that when i manually open the egr valve, the engine doesn't die. It just runs rougher and runs like crap. I read several places that the engine should stall out. Maybe there is a clog in the exhaust system that isn't letting enough exhaust into the valve? any ideas?