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Check Engine - Code P0401


LS400er

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Hi,

I just had the starter replaced and also the EGR tube, Valve cover gaskets in my 95 LS.

The next day i see fumes coming from the Engine (Near EGR Tube area), no visible oil leak though, then came the Check Engine light. Did a diagnosis check, it turned out to be "P0401 - Insufficent EGR flow, OK to Drive."

Any body has any clues ? Did the mechanic do something wrong or miss something ?

Thanks.

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skperf - on my '92 LS-400, I didnt have to remove the head, just the intake manifold. Why would one have to remove the head, seems odd to me ?

LS400er - the tube he replaced bolts on to the back of the air intake chamber. I dont believe that is the source of the problem. I agree with sk, there is some kind of blockage or the missed puttting a line back on.

That is alot of work to replace starter & EGR tube.

If you dont mind, how much did that set you back ??

Jeff

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Thanks for the reply.

First of all, How bad is this condition ? Does this need a immediate fix or can this wait to be fixed. The run runs great, except for those fumes when its Hot.

This was the first time the mechanic had to replace a starter on a LS, I saw it was a tedious job. He had to remove the water-coolant joint tube and hence the EGR tube attached to it. Actually we found that the EGR tube was cracked and had to be replaced. (All this cost me $600, parts & labor)

Most of the time i was there while he was working on it. There were 2 screws left while he was done fixing the car. He said 2 was very few for such a big job.

I dont think if he has missed any hose. The EGR tube is connected on both ends by 4 screws and metal gaskets.

What kind of blockage could possibly be there ? I see the fumes coming from the air intake chamber area.

What is "Head" you were referring to ? Is there a way one can remove the starter with out removing the water-coolant joint ?

Thanks.

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at least on my '92 LS400, I had to remove air intake chamber & intake manifold to get to my starter. Attached is pic. On a '95 is yours located here ?

I would look into getting that trouble code check soon. Or have mechanic clear the code, & see if it comes back in a few days. Something smoking underneath your hood is not normal.

what kind of mechanic is that!!! Only having 2 screws left over from a big job is nothing....

There should not be any......find a another mechanic that doesnt have that attitude.....

He is not very conscientious about his work.....

Nothing short of right is right.....

Jeff

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p0401 - exaust gas recirculation flow incufficient detected.

After the engine is warmed up and run around 50 mph for 3 to 5 minutes, the egr gas temperature sensor does not exceed 86F above the ambient air temperature. this error code will appear only if this happens on at least 2 trips.

Check the sensor first.might be just a sensor. it is located right next to the starter so it either was damaged or he might forget to connect it back.

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I meant to say the manifold.

There is a trick to remove the starter by using a few very long extensions to get way in the back to reach the 2 bolts .It can been seen from the front with a ilght.I can;t remember if you had to move anything out of the way first to look down the underneath of the manifold.

Then you slide it out the back of the engine and undo wiring. A lexus tech at one of our local meets told me how to do it.

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Thanks VMF & Sk.

So according to the Manual its the EGR Valve OR EGR gas temp Sensor OR EGR motor circuit OR ECM (i dont want to think about this)

The Diagnosis talks about Lexus Meter to read the temperature, is this only done by Dealer ? or any OBD2 reader can read this ?

Can my mechanic do all this tests ?

I remember plugging in two sensor circuits at the rear of the starter, i plugged them in myself and heard the clicks. Does it make a difference If i plugged them in the wrong sockets ? I mean do they have to go in exactly the designated sockets or is it OK if they are plugged in the either of them ?

Should I reset the engine check code and see if it comes again ? It was reset once and it came back.

Should I go to the Dealer or see the same mechanic ?

Thanks.

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