I got a po401 code, so I replaced the EGR Vacuum Solenoid, & then got a po402 code (1 Viewer)

[GregMacd]

I have a 95 Landcruiser with 245,000 miles on it. I'm in California, and need to get a smog check. The CEL came on about 5 days ago, and I scanned it and it said I had a po401 code ("Exhaust EGR Flow Insufficient"). I noticed that the EGR Vacuum Solenoid had a green sticker on it, so I assumed it was the original one and broken. I then replaced it with a new one with a blue sticker. After replacing the EGR Vacuum Solenoid, my scanner initially stated "egr not ready". Then after about 40 miles of driving, the CEL came on, and my scanner then read the po402 code (""Exhaust EGR Flow Excessive"). So basically, I went from EGR flow insufficient to EGR flow excessive after replacing the EGR Vacuum Solenoid!

I had replaced the O2 sensors before and after the cat about a week before replacing the EGR Vacuum Solenoid, because I was getting a po420 code. That code hasn't come back yet, although my scanner still states "cat not ready."

* Does this give me any hints as to what to do next to pass the CA smog test?
* Are their any recommended Landcruiser repair places in the Oakland, CA area that could figure out the problem, so that I can minimize my expense and the number of parts I need to replace?

Thanks,

Greg

 

[surfpig]

EGR vacuum modulator. And make sure you vacuum lines are intact and clear.

 

[GregMacd]

EGR vacuum modulator. And make sure you vacuum lines are intact and clear.

Thanks! I think I'm getting my terms confused. When I google “EGR vacuum modulator” I see pictures of the EGR Solenoid, part W0133-1749037, which is the one I replaced: Amazon.com: OES Genuine Exhaust Gas Recirculation Vacuum Solenoid for select Toyota Land Cru...: Automotive

 

[surfpig]

Thanks! I think I'm getting my terms confused. When I google “EGR vacuum modulator” I see pictures of the EGR Solenoid, part W0133-1749037, which is the one I replaced: Amazon.com: OES Genuine Exhaust Gas Recirculation Vacuum Solenoid for select Toyota Land Cru...: Automotive

That's the one I was thinking of. The actual valve (solenoid) is an electric part, located under the manifold.

 

[Pin_Head]

The EGR valve may be stuck open after long term inactivity. If so, it should idle poorly.

 

[GregMacd]

The EGR valve may be stuck open after long term inactivity. If so, it should idle poorly.

Thanks! The idle does seem to be a bit rough. Is there a way of repairing the EGR valve other than replacing it? Is the EGR valve difficult to replace?

 

[GregMacd]

Thanks! The idle does seem to be a bit rough. Is there a way of repairing the EGR valve other than replacing it? Is the EGR valve difficult to replace?

Is there a way to spray some WD40 or carberator cleaner into the EGR valve to unstick it?

 

[Tedward]

I removed the EGR valve and took to cleaning on the bench. Lots of spray and air and q-tips and rags. It was pretty gunked up in there and no way was sealing tightly.
After cleaning, I applied vacum, and checked that it was opening and closing correctly.

 

[GeoRoss]

Thanks! The idle does seem to be a bit rough. Is there a way of repairing the EGR valve other than replacing it? Is the EGR valve difficult to replace?

One way to test the EGR valv is to apply vacuum while the truck is running. It should stumble/stall.

 

[Pin_Head]

Whack it on top of the actuator can with the handle of a screw driver and see if it idles better. You may need to do this a few time to free it up. Of course you can also take it off and clean it by dipping the lower part in carb dip and then lubricate the actuator rod with graphite or teflon lube.

 

[GregMacd]

Whack it on top of the actuator can with the handle of a screw driver and see if it idles better. You may need to do this a few time to free it up. Of course you can also take it off and clean it by dipping the lower part in carb dip and then lubricate the actuator rod with graphite or teflon lube.

Thanks! I'll try that. Is the EGR valve difficult to remove?

 

[landtank]

If the two hoses on top of the modulator are reversed you will get a P0402

 

[surfpig]

If the two hoses on top of the modulator are reversed you will get a P0402

Makes sense, he went from a too low to a too high condition.

 

[GregMacd]

Makes sense, he went from a too low to a too high condition.

Thanks! I thought I was careful about not switching the lines by tying a white and green bread tie on them, but I just tried switching them and I'm driving right now so I'll let you know how it goes

 

[bmw635]

I am trying to figure my P0401 also. Diagnose first before throwing parts at it so you have a baseline to work with.

1-Check all vaccum hoses.
2-Blow into the bottom of modulator- it will leak if diaphram is torn then replace.
3-Check EGR VSV by disconnecting the gray plug and ohm out the 2 yellow wires like here: Checking VSV for EGR easy way P0401 If no resistance, it's dead. You could also get 9V battery and power the 2 yellow wire to hear click, also power the other 2 wires for the EVAP VSV ( next to EGR VSV) to hear click also. Replace VSV if dead.
4-Clean out EGR and check with vacumm while idling. Engine should stall/ die when apply vaccum.

Still getting P0401 after confirming EGR VSV is dead and replace with "like" kind" so may be the wrong VSV is used?

This is the replacement:

This is the dead one:

 

[bakolc80]

Watch these videos to test the system. Mine was the intake manifold egr passage needing to be unclogged.

 

[GregMacd]

If the two hoses on top of the modulator are reversed you will get a P0402

Landtank, I think you were right! I must have reversed the vacuum lines. I reversed them back yesterday, drove about 50 miles and completed a drive cycle, and my scanned indicators for the EGR and CAT went from "not ready" to "ready" without the CEL coming on. Time to get a smog check. Thanks for your help!

 

[landtank]

Glad to help

 

[GregMacd]

Glad to help

I just passed the smog test! thanks again