P0401 related to Catalyst Monitoring Y/N?

[73sport]

All,
The 1MZ threw a P0401 code over the weekend. Using AutoTap software my 95 1MZ always shows "incomplete" on "Catalyst Monitoring Status".

Do 95 1MZ's report this condition or is my Cheapo Software interpeting things wrong? It's shown incomplete since I connected to it the 1st time in 2010-03 of this year. But it had other issues then too!

Does your 95 ever show Complete?

Thanks. . .
73

[projektvertx]

Wait, I thought P0401 was related to EGR flow???

And if your cat is failing (again), crap.... We all know mine is going soon

[73sport]

Originally Posted by projektvertx

Wait, I thought P0401 was related to EGR flow???

And if your cat is failing (again), crap.... We all know mine is going soon

<<< I still have original cat, but it smells like fart out the hole. Is this a sign of something bad, the sulpher smell?

I was trying to find your name last night so I could warn you of the empending doom! Glad your reading along.

Yes, it is. I'm just trying to figure out if I missed something back when the other issues came into play? Plugs, coils, O2 sensors. . . ect

2, 4, 6, All lean, Why? Need Help!

==
CODE P0401, Exhaust GasRecirculation Flow Insufficient Detected. After the engine is warmed up and run at 80 km/h (50 mph) for 3 to 5minutes, the EGR gas temperature sensor value does not exceed 40
C (104
F) above the ambient air temperature, (2 trip detection logic). . .
==

[73sport]

#1 Does your 95 1MZ ever show "Catalyst Monitoring = Complete"?


#2 Why does Bank 1 Sensor 2 always read 99.2%? The sensor has a full range of output in mV and seems healthy, but the number remains fixed at all times. I'm sure its normal, it just seems odd!

[projektvertx]

Here is a Toyota TSB they issued in '03 about sulfur smell in exhaust:

http://www.tegger.com/hondafaq/tsb/s...l/eg003-03.pdf

Here are some additional thoughts:

-Unburnt fuel, caused by, what I wouldn't know, since everything is brand new
-Cam timing slipped off a tooth or something?
-Vacuum piping? I would check that along with the EGR.

[projektvertx]

Originally Posted by 73sport

#1 Does your 95 1MZ ever show "Catalyst Monitoring = Complete"?

I have no way of checking that unfortunately, I don't have the proper rigging to do so If it can be done easily, I can arrange to do it.

#2 Why does Bank 1 Sensor 2 always read 99.2%? The sensor has a full range of output in mV and seems healthy, but the number remains fixed at all times. I'm sure its normal, it just seems odd!

Bank 1 Sensor 2 is the one facing the radiator no? It's always reading 99.2% I would fix the EGR first and work from there, because I doubt a new sensor would be defected already. Maybe the heating unit is not functioning properly? Did you buy a universal one, or was it an OEM replacement? If it was a universal replacement, I would check your wiring crimps for the heater, maybe something came loose? This symptom confuses me

[73sport]

bank1 sensor 2 is the CAT!

bank1 sensor 1 = 1, 3 ,5
bank2 sensor 1 = 2, 4, 6

But thanks for the article!

[projektvertx]

Originally Posted by 73sport

bank1 sensor 2 is the CAT!

bank1 sensor 1 = 1, 3 ,5
bank2 sensor 1 = 2, 4, 6

But thanks for the article!

Ah woops, my bad it gets real confusing with the numbering

[73sport]

^^ No worries. . . You need an OBDII scanner and software.

In case the linke goes away here is the text:

Technical Service BULLETIN February 24, 2003, EG003-03
Title: SULFUR ODOR FROM EXHAUST
Some owners of Toyota vehicles may experience a sulfur–like or “rotten egg” odor from the exhaust system. Sulfur is a natural component of crude oil from which gasoline is refined and the amount of sulfur can be decreased through the refining process. The amount of sulfur in fuel sold in California is regulated, however gasoline sold in other states can have substantially higher sulfur content. Sulfur content also varies considerably between gasoline brands and locations.

Repair Procedure:
A sulfur odor emitted from the vehicle’s tailpipe does not necessarily indicate that there is an issue with the engine’s running condition, but is most likely directly related to the fuel.
If the vehicle is exhibiting an excessive sulfur odor, the following checks should be performed:
�� If the MIL light is ON, check for DTCs and repair as necessary.
If no trouble is found after performing the above check, recommend the customer try a different source of fuel.
Replacement of oxygen sensors, air/fuel ratio sensors or catalytic converters will not reduce the odor and will therefore not be considered warrantable.

[Jason.MZW20]

^^

Toyota replaced both of my exhaust manifolds (with pre-catalysts) and the main catalyst on my 1GR Tacoma for a sulfur smell. There was a TSB on it. Needless to say, the revised catalysts did not emit that smell.

P0401 could be related to your ECU retarding timing under heavy load. Remember, the EGR system cools the combustion chambers. The newer 1MZs operate the EGR nearly all the time, but yours is a little different. Yours will cut off at about 4200rpm or at WOT, but the cooling effects should remain before the cut-off.

You can test the EGR VSV, test the vacuum modulator, and clean the EGR valve. Unforunately, my 2000 1MZ's EGR system is quite different as it's a constant vacuum type system, not a vacuum modulated system.

Oh and B1S2 should see a nearly constant readout. I wouldn't be surprised if the catalyst monitor has a very specific driving pattern. The early ones were nearly impossible to set correctly. Same with the EVAP for 2000 models. Sometimes it would set within 3 days, other times it would take over a week. It just depends on the conditions.

[73sport]

Originally Posted by Jason.MZW20

^^

Toyota replaced both of my exhaust manifolds (with pre-catalysts) and the main catalyst on my 1GR Tacoma for a sulfur smell. There was a TSB on it. Needless to say, the revised catalysts did not emit that smell.

haha - I think mine might be out of warranty

Originally Posted by Jason.MZW20

P0401 could be related to your ECU retarding timing under heavy load. Remember, the EGR system cools the combustion chambers. The newer 1MZs operate the EGR nearly all the time, but yours is a little different. Yours will cut off at about 4200rpm or at WOT, but the cooling effects should remain before the cut-off.

You can test the EGR VSV, test the vacuum modulator, and clean the EGR valve. Unforunately, my 2000 1MZ's EGR system is quite different as it's a constant vacuum type system, not a vacuum modulated system.

I'll be looking it over much closer this time. I did the EGR crud clean out a year ago. Can't imagine the pipe/valve is plugged. Eitherway I have some testing to do. You really think the ign retard could pull this down like that??? <scratch head>>

Originally Posted by Jason.MZW20

Oh and B1S2 should see a nearly constant readout. I wouldn't be surprised if the catalyst monitor has a very specific driving pattern. The early ones were nearly impossible to set correctly. Same with the EVAP for 2000 models. Sometimes it would set within 3 days, other times it would take over a week. It just depends on the conditions.

the sensor voltage and response is good. Just the ECM readout says 99.2% all the time. I never figured out if it was realted to the fart smell, and the "Catalyst Monitoring = incomplete".

I tried to keep this in the other thread as I thought its related to her past! But hey, I'll take help in any way it comes!

Clicker V V
2, 4, 6, All lean, Why? Need Help! That's page 7, post #92 in the MZ saga. . .

[fenixus]

not sure if it helps bro, probably you know it already, but this is probable trouble area for P0401 coming from gen4 1mz-fe (i think they didn't change it much since gen3 though except for what Jason.mzw20 posted):

- EGR valve (stuck closed)
- Open or short in EGR gas temp. sensor circuit
- EGR gas temp. sensor
- Open in VSV circuit for EGR
- VSV for EGR
-Vacuum control valve
-Vacuum hose disconnected or blocked
-ECM

page DI-292 of gen4 Diagnostics manual (from camrystuff).

it doesn't seam like it has anything to do with cat converter which might be a separate issue on your ride (test stays incomplete) ... try fixing the P0401 and see if it helps getting that test completed
... i know easier said than done ... i've got my own nightmare on my gen4.5 5s-fe ... it's a real PITA, once i fix one thing it comes up something else is wrong!

also i'm pretty sure there is a specific driving pattern for completing the test. as Jason.mzw20 posted, getting EVAP test completed on gen4 takes sometimes 3 days and other times it takes up to a week for ECU to mark it done.

try pm'ing ajkalian, he's got the book of all those drive cycle magic for getting the ECU internal testing done, it's different for every model, year, etc.

i wouldn't worry what % the o2 sensor is reading for that matter, mine stays at 0% always, might be a software glitch or lousy ECU programming. if sensor's output voltage and range seem correct (and is not sluggish), i would assume that's OK.
i have never heard anyone admitting that Toyota does a good job on programming their computers so far it seems they can't do that right even on latest models haha!

[73sport]

Thanks! Hmm. . . Me's thinks I'm on the right path, just need time to do it now. Funny, always looking up stuff fer others and now mine calls out..

Here's what I put in the original thread. It follows your thoughts there pretty close. Thanks For Yer Input Fen!

Paste!

blah blah from other thread. . . As usual, all codes spit by this ECM come seconds after turning the key on to go somewhere. Engine was warm and car was run on short trips in town today that DO NOT meet the below criteria so why this code now? Is this normal for this code?

CODE P0401, Exhaust GasRecirculation Flow Insufficient Detected. After the engine is warmed up and run at 80 km/h (50 mph) for 3 to 5minutes, the EGR gas temperature sensor value does not exceed 40C (104F) above the ambient air temperature, (2 trip detection logic). . .

OK - Cool, not fatal so it'll be driven that way for a few days until I can look at it.


Votes:
1) blocked EGR plumbing
2) temp sensor gone bad
3) vsv lost signal, died
4) hose/vacuum leak to EGR valve
5) modulator defect
6) EGR valve failure
7) Other: _________

I'll grab a vacuum gauge and start probing on mon/wed! Because I've stuck my hand on that cast iron erg valve after long drives and its hardly hot, its been defunct for a bit I think. Maybe the pipe below is plugged? I'll try forcing air down it and see what it thinks about that.
But if the valve never opens, then exhaust would never heat it. There the things I need to figure out. . .

[JohnGD]

Did the system ever go into closed loop? I wonder what other monitors require closed loop to complete.

[fenixus]

Originally Posted by JohnGD

Did the system ever go into closed loop? I wonder what other monitors require closed loop to complete.

i'm pretty sure oxygen sensor testin require closed loop to complete. not sure about others non-continuos ones. i think rest of them needs driving under varying scenarios (cat, egr, evap, etc.)