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EGR P0401 Code in a 98 Taco 2.7 Ltr

7K views 6 replies 4 participants last post by  Whitetoy 
#1 ·
I have a 1998 4wd Taco Ex cab,with a 2.7 motor that has 420K miles on it. The CEL came on and the code was P0401 "insufficient EG flow to EGR system". I tried cleaning the EGR, roto-rooting the tube the connects the EGR to the exhaust manifold and cleaning the EGR solenoid. When none of that worked I even replaced the EGR for $130 bucks and I still get the CEL.

The truck is running fine. I don't want to disconnect the system as some have suggested in other threads. Any ideas?

Is it possible that the temp sensor is shot? Those things run about $120 so I'd really like to know if its the likely culprit based on my description of the problem.

Side bar: When I removed the new EGR during my roto-rooting effort I did notice that the inside of the new valve was getting some fouling for the week that I ran it. It wasn't as bad as the original but it certainly had a coating of fouling indicating exhaust gas flow.

thanks
 
#2 ·
I'm not familiar with the 2.7L, but is it possible flow out from the EGR valve is obstructed? You mentioned cleaning the line from the EM to the EGR, but if the path from the EGR is blocked it could prevent flow and maybe trigger that CEL? It might have a different code instead, but thought I'd try to get the ball rolling a little
 
#4 ·
Had the exact same problem with my 2.7 just after I bought it. Cleaned the valve, replaced the modulator (with used) but did not clear the P0401. Finally, I removed the temp sensor, cleaned the tip real good, and re-installed it. This cleared the P0401. Seven months later, the code returned, and I cleaned it again.
 
#5 ·
Temp sensor is what I'm thinking since the truck is running fine. I've already cleaned the EGR solenoid filter and inside the base with carb cleaner. I think I'll try cleaning the sensor first before I buy a new one.

Hopefully this will work.
 
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