P0133, 130, and 401 - Data Point (1 Viewer)

[bkgiii]

P0401 - Data Point - CULPRIT FOUND??

For those of us who don't have the time , and end up visiting the dealer, here's a data point:

O2 Sensor, VSV set, vacuum hose, and a free Lexus key fob......all for the low low price of $566.47.

Additional info from the OBDII printout, whatever all this means:

Number of DTCs: 3 ^
P0130 02 Sensor circuit Malfunction, Bank 1 Sensor 1
P0133 02 Sensor Circuit Slow Response, Bank 1 Sensor 1
P0401 EGR Flow Insufficient

Calc Load 41%
Engine Speed 1859 RPM
Coolant Temp 176.0 deg
Intake Air 96.8 deg
CTP SW Off
Vehicle Speed 53 MPH
Short FT #1 0.7%
Long Ft #1 2.3%
Fuel Sys #1 CL
Fuel Sys #2 Unused
FC IDL Off
Starter CIG Off
A/C Sig Off
PMP SW (NSW) OFF
Stop Ligh SW OFF
Engine RUn Time 96


Anything in all that above stuff I need to know / worry about?

 

[landtank]

yes, the $566.47

 

[bkgiii]

Yeah...that's right, Rick.......drive it in a little deeper!

With maw-in-law in ICU for 7 weeks running, simply no time to attempt it myself....oh well....priorities.

To make it worse ...I think i posted this up at 12:15, and at 1:40 the CEL came on again...a quick dash back to the dealer came back with the same code...P0401. Back in the shop on Monday, I guess.....

 

[OGBeno]

Damn that hurts!!!!

 

[Lockd97]

Calc Load 41%
Engine Speed 1859 RPM
Coolant Temp 176.0 deg
Intake Air 96.8 deg
CTP SW Off
Vehicle Speed 53 MPH
Short FT #1 0.7%
Long Ft #1 2.3%
Fuel Sys #1 CL
Fuel Sys #2 Unused
FC IDL Off
Starter CIG Off
A/C Sig Off
PMP SW (NSW) OFF
Stop Ligh SW OFF
Engine RUn Time 96


Anything in all that above stuff I need to know / worry about?

This is the capture data meaning that this was the conditions when the OBDII flagged the failure. FYI

 

[semlin]

the vsv replacement may or may not cure your egr code in the long term although the fact they replaced some vacuum hose hopefully means they checked over the rest of the system. take a look at the EGR discussion in the FAQ. You should check the EGR modulator filter condition (takes about 30 seconds).

 

[bkgiii]

Yep, Semlin...I looked at that discussion previously (a week or so ago) when I was planning on carving out time to do this job myself. Good write -up to you and Landtoy, by the way.

The tech assured me that he checked that AND cleaned it, along with hose replacement which he performed. I suspect, based on how apologetic they were, they're going to no charge me on Monday....we'll see about that!

Thanks for the FAQ reminder.

 

[semlin]

if he cleaned the modulator filter how dirty was it? I know the FSM says to clean it with compressed air but I think the only way it can get dirty is if the modulator or egr valve fails/is failing or your throttle body is really really dirty. my replacement mod filter got a small black dot on it when i first installed it (which i think was residual crud somewhere) then zip since.

oh why dont i just cut to the chase and tell you to replace the modulator...

by the way it was landtoy not landtank who did most of that write up.

 

[bkgiii]

Not sure how dirty it was......or if he cleaned it. I would hope he did, but I'll be certain to mention that when I take it back in.

Authorship error changed, BTW..thanks.

 

[bkgiii]

Persistant P0401.....

Two more trips back to the dealer on this problem. P0401 continues to show up after aforementioned service, and the dealer seemed stumped this afternoon. They say the monitor does NOT show a code when driving, but it DOES show back up when they bring it back in. I don't know what all THAT means, but the CEL continues to come on with the persistant P0401.

I re-read a couple of earlier posts, and need y'all to clarify a couple of things for me:
(1) I DID notice I have a so-called 'bad' green-top modulator rather than the so-called 'good' blue top one. I did NOT see the part # of the 'blue' one...is it a different part #?
(2) In another post, someone mentioned there are TWO VSVs......my dealer did not mention that, and I'm wondering, on my '96, are there really two?
(3) In the FAQ, there's reference to a modulator FILTER......is this a serviceable / replaceable part or integral to the modulator? (in #1, above?)

I'm giving them ONE MORE CHANCE in the morning to get this right. At least they have the decency to not charge me for all this extended diagnosis work, and in this instnace only I'm getting killer deal on whatever additional parts are needed..

Suggestions?

 

[semlin]

-VSV just stands for vacuum switch valve. It is an electrical switch that opens or closes a vacuum line. my 93 has 2 next to each opther under the air intake plenum, one for the EGR and one for the PAIR system, but I don't think you have a PAIR system on a 96 so you should have only one VSV I think.

-the modulator filter is only sold with a modulator. It is a disc of white fibreglassy stuff. If you pop the plastic cap off the modulator gently with your hand or a screwdriver you can inspect ity yourself. It can be removed and blown out with compressed air but that leaves the question of how it got clogged in the first place. To me that is like emptying out the bucket you have under the leaky sink instead of fixing the leak.

Making an informed guess, I would check the modulator filter yourself and if it is even slightly dirty looking in there, replace the modulator yourself for $40 and see if that works. forget what colour it is, the problem is once they fail they admit carbon into the vacuum lines which causes blockages and may damage the vsv.

Otherwise, here's a list of the questions for your tech...

-were the modulator filter or vacuum lines full of carbon crud before the recent service? If so, replace the modulator, clean out all the vacuum lines again (and clean the throttle body if you have not already done so since carbon might be able to get in that way too) . Hopefully there has not been time to wreck the vsv again.

-did/does the truck pass the F S Manual egr vacuum tests? if not, why not?

-did they test the egr valve and egr temp sensor?

-have they checked to see if the passage in the intake plenum between the egr valve and the air intake is clogged with carbon? if not, check it and clean it.

-have they checked to see if the throttle body was clogged with carbon and did they ensure the egr vacuum ports on the top of the throttle body were clear and functioning?

-have they checked that the vacuum line from the egr valve down to the VSV is not plugged where it passes through the intake plenum?

-did they remove the air intake plenum to replace the vsv as specced in the fsm or did they take the shortcut? If they removed the plenum then they should at that time have cleaned any carbon out of it and the throttle body too, and I would argue with them about paying for them to be removed again to do those things now.

 

[bkgiii]

Re-read all those threads..got up the nerve...and here's ONE thing I found about 10 minutes ago. I see what you're saying, now: the filter is that fiber disc which, In my case, is pretty much nonfunctional. I cleaned it, the modulator, and all hoses connected thereto, reassembled, and disconnect battery and the main fuse.....in 20 more minutes and a little driving, I'll let you know if the CEL comes back on.

Thanks a whole bunch for the info...I really appreciate that and the questions to ask in the morning.

More in a bit.....

 

[semlin]

Sorry, checking back at your earlier post did the Lexus guy really tell you he cleaned that?? That modulator is toast and is admitting carbon from the exhaust. GET A NEW MODULATOR!!!

You have had lots of carbon in your system. Have the dealer make sure the throttle body egr vacuum ports are not blocked, and also that there is no blockage where the vacuum hose out of the egr valve goes through the intake plenum.

I would clean the throttle body by hand (removed and cleaned not cleaned with one of those spray chemicals) and clean out the passage in the intake plenum between egr valve and intake (requires removal of egr valve and throttle body). I am pretty sure those will be in bad shape too.

Once that is done I suspect your problems will be over.

 

[bkgiii]

Well, after about 40 minutes / 30 miles......I'd swear this thing is running / idling / shifting smoother....and NO CEL (yet). I'm hoping this cures it as you said, but I feel an order for a new modulator coming.

TO clarify, the dealer (Toyota, not Lexus) cleaned the throttle body, not the modulator....I'm now convinced they didn't even check that, and will confirm that in the morning. the tech DID mention this afternoon that he'd like to clean the intake and re-check the VSV..

..keep you posted.

 

[Beowulf]

Kit,

I agree with Simon's assessment and with his advice to replace that modulator. As you now know, it can be replaced with no tools and about 5 minutes of time.

I also agree with the theory that a failed/failing modulator takes out the VSV for EGR. There are TWO VSV's under the intake; one of them is the VSV for EGR. I don't recall what the other is for but your '96 and my '97 have two under the intake.

Be sure to remind your mechanic that the P0401 is a TWO TRIP (i.e. DRIVE CYCLE) logic. It sounded to me that they were fixing something and taking it for a drive and not getting a code; therefore proclaiming the problem fixed and turning it off. Then you drive off, complete a drive cycle, and the code trips.

-B-

 

[bkgiii]

Thanks B.....they were aware of the two drive cycle logic. THey also said the modulator was toast (duh!), but EGR was vine. Other VSV may go to the cannister according to the tech off the top of his head.