P0401 Error...really worry about it? (1 Viewer)

[plarsen111]

I have the classic code that so many have talked about. I replaced the modulator (which was indeed dirty).

My question is, should I really worry about it that much? I know some folks have mentioned the check engine light is fickle, and comes on quite easily. I just want to be prepared when I take it to the mechanic on Monday.

Thanks,

Phil

 

[dontblink]

I'm getting ready to pull the whole damn EGR system out. It's useless, IMO.

That said, I've been running my 80 with a P0401 for a few months now, with no ill-effects to report, besides 200 miles per tank.

 

[plarsen111]

The good news is I am getting 325+ miles to the tank. Maybe it is nothing to worry about. I am going to have a mechanic look at it Monday. Will keep you posted.

 

[Flank]

The check engine light is not "fickle", and does not come on in a whim. It denotes something is wrong. I've never heard of the CIL coming one "just because", it does not do this. It will always throw a code. Suggesting that the light is "fickle" is just plain wrong.

As to whether or not the EGR system and the P0401 code is important, that depends. It depends on whether or not CILs bother you, and depends what the laws are in your area. In many areas, you cannot pass inspection without your system in ready mode with no CILs, so it is a big deal. In many areas they look for emissions alterations, such as alterations to the EGR system, so it is a big deal. That being said, the truck can perform usually fine without the EGR system and many have disabled it and tricked the computer by installing a very cheap resister to fool the computer.

 

[newtomelx]

????

I had a 401 code, replaced modulator with a new blue top unit, reset codes, drove the cycle and now have a 402 code. I have got new vacuum hoses in hand along with the dorman vsv replacement from advance auto and will report back after the weather improves to give me time to replace these to see what happens then. I do not understand from what I have read does this indicate that the passage way in the intake for the EGR valve is not clogged.....with all the carbon and the disintegrated diaphragm in the modulator I cannot believe that this is the case.

 

[plarsen111]

"That being said, the truck can perform usually fine without the EGR system and many have disabled it and tricked the computer by installing a very cheap resister to fool the computer."

I would love to know how to do this. Youtube Video?

 

[Wiscolandcruiser]

Search "egr desmog 80" you should find something. Also check your local emission laws before you go ripping out your egr system.

Sent from my busted to s*** EVO4G

 

[plarsen111]

We don't have any emissions tests where I live.

 

[sct11]

What year is your 80?

 

[wearsabrowncoat]

I get that code about once a year when the outside temp drops with the season. Reset it with my scan gauge and no noticeable issues. That seems fickle to me.

 

[plarsen111]

I am driving '97 Land Cruiser.

 

[Splangy]

I had a 401 code, replaced modulator with a new blue top unit, reset codes, drove the cycle and now have a 402 code. I have got new vacuum hoses in hand along with the dorman vsv replacement from advance auto and will report back after the weather improves to give me time to replace these to see what happens then. I do not understand from what I have read does this indicate that the passage way in the intake for the EGR valve is not clogged.....with all the carbon and the disintegrated diaphragm in the modulator I cannot believe that this is the case.

the 402 code is an excessive EGR code. The ECU is detecting EGR function when it shouldn't.

 

[newtomelx]

Quote:
Originally Posted by newtomelx
I had a 401 code, replaced modulator with a new blue top unit, reset codes, drove the cycle and now have a 402 code. I have got new vacuum hoses in hand along with the dorman vsv replacement from advance auto and will report back after the weather improves to give me time to replace these to see what happens then. I do not understand from what I have read does this indicate that the passage way in the intake for the EGR valve is not clogged.....with all the carbon and the disintegrated diaphragm in the modulator I cannot believe that this is the case.

the 402 code is an excessive EGR code. The ECU is detecting EGR function when it shouldn't.


Does this mean that the egr valve is probably stuck in the open position, I do not understand how replacing the modulator would make the code change from a 401 to a 402?? What am I missing here?

 

[Impreza]

"That being said, the truck can perform usually fine without the EGR system and many have disabled it and tricked the computer by installing a very cheap resister to fool the computer."

I would love to know how to do this. Youtube Video?

It's really easy and I still have a few resistors left over. I haven't seen a EGR related light in years. Pm me if you want me to mail you my leftovers. Just my ECU will never go back to ready status.

 

[Corbet]

I've been running with the P401 for 6 years and 80,000 miles. Someday I'll make the time to track down the cause. I just clear it once in a while to make sure nothing else has tripped the CEL.

 

[plarsen111]

Thanks Corbet. I have been running with mine for 80k miles too. How many miles do you have? I am currently at 270k. With that info, I might have to cancel appt.

 

[newtomelx]

Houston Texas

Well this is all fine as my truck actually seems to run really well and am getting a consist 16-17ish mpg on the hwy. My issue is with the state of Texas and I must have a clear ecu, no not ready mode and no codes or no inspection sticker! This is my dilemna, so the resistor mod does not work for me. I must have a clear and ready ecu. Must fix issue, just need to confirm what that exactly is.

Sorry for the thread hijack!!

 

[Corbet]

Thanks Corbet. I have been running with mine for 80k miles too. How many miles do you have? I am currently at 270k. With that info, I might have to cancel appt.

162K

Well this is all fine as my truck actually seems to run really well and am getting a consist 16-17ish mpg on the hwy. My issue is with the state of Texas and I must have a clear ecu, no not ready mode and no codes or no inspection sticker! This is my dilemna, so the resistor mod does not work for me. I must have a clear and ready ecu. Must fix issue, just need to confirm what that exactly is.

Sorry for the thread hijack!!

Remove the CEL bulb from dash display? Or do they plug in for verification?

 

[carlosfj80]

Well this is all fine as my truck actually seems to run really well and am getting a consist 16-17ish mpg on the hwy. My issue is with the state of Texas and I must have a clear ecu, no not ready mode and no codes or no inspection sticker! This is my dilemna, so the resistor mod does not work for me. I must have a clear and ready ecu. Must fix issue, just need to confirm what that exactly is.

Sorry for the thread hijack!!

That's great mileage! You driving at 55mph and no more?

 

[Wrench]

It's really easy and I still have a few resistors left over. I haven't seen a EGR related light in years. Pm me if you want me to mail you my leftovers. Just my ECU will never go back to ready status.

Same here. Did the resistor mod. EGR codes defeated!