Check Engine Light

2001 Toyota Tacoma - 2.7 engine. Check engine light has been on for some time now. Code suggests the EGR system. Replaced the EGR valve - however this did not seem to help for very long. What other components in the EGR system should I consider looking into. Hope this helps? Thank you for your assistance & suggestions. KK

 

The EGR system has many components: EGR valve, EGR modulator, EGR temp sensor, EGR vsv, and many EGR vacuum lines.
However, that valve is typically the item that is replaced, but is unlikely the issue, as you have found out.

The valve can be ruled out with simple testing (no tools required). This is also the most expensive and difficult, to replace.

There are several trouble codes that relate to EGR. Determining that is the first thing to do.

Check the easy stuff first, the vacuum lines. One or more could be disconnected, or split, or old and brittle. There are tests of the modulator that are spelled in most manuals (FSM, Haynes).

In my case, the solution for my P0401 code was to remove and clean the EGR temp sensor. The only special tool I needed was a 14mm brake-line wrench to remove/replace it.

Good luck

 

Thanks very much for the update! Hopefully I won't have all that much trouble locating & then removing the EGR temp sensor. I'll see if I can find step by step instructions regarding this component. SP

 

Just picked up a 99 SR5 and theyre saying the EGR valve is the culprit for the check engine light. I will take it back today and get the exact code its throwing, but how can you test the valve to see if it is indeed bad? That stupid valve is like $140

 

https://youtu.be/BmmdpSsKeWE

 

What was the code? I have been fighting the check engine light since I bought my '03. It's good now, but for how long??

 

I will fail mechanically by either not closing all the way (stuck open), or stuck closed.
Very simple to diagnose.

If it stuck open, then this introduces a large vacuum leak, and the idle will be very rough.
If the idle is smooth, then its not stuck open.

If it is stuck closed, you can eliminate possibility by applying intake vacuum directly to the
valve port, while idling. If that opens the valve (as it should) the idle will become rough.
For this test, I just disconnect the valve vacuum line (at the valve), connect a short piece
of similar tubing to the valve and suck on it, like a straw.

 

The truck idles and runs fine. So I assume it’s not the valve. I did use a scanner to get the code, which is P0401

 

Used to be able to add a resistor and leave unplugged until you get parts to fix it.