Check engine light on dash

[Ed Purmals]

Hi. My 1997 LX450 , "check engine" dash light that has a picture of an engine came on recently. I'm a retired mechanic so I checked fluids and engine over pretty good and couldn't find anything wrong.
What is this light connected to and what might I check that I have overlooked. Manual says it's engine electrical and to take it to dealer....right!! There is no Lexus dealer here and the closest Toyota one is a gangsta! Any suggestions would be appreciated.

Thanks

Ed

 

[soggy60]

IF you have the FSM, there's instructions on which two connectors in the diagnostic plug to 'short together' and read a flashing light pattern....the pattern can tell ya what's wrong.

My 'hear-say' based knowledge : O2 sensors are a common cause of the check engine light....

 

[CJF]

IF you have the FSM, there's instructions on which two connectors in the diagnostic plug to 'short together' and read a flashing light pattern....the pattern can tell ya what's wrong.

Not on a 97 (OBDII).

Ed,

Go by pretty much any auto parts store and they'll read the codes for you for free. Write down ALL the information (not just, "the guy said it was probably...") and report back.

Curtis

 

[OB-1]

IF you have the FSM, there's instructions on which two connectors in the diagnostic plug to 'short together' and read a flashing light pattern....the pattern can tell ya what's wrong.

Actually, IIRC, that's only true for our rigs (pre-95). Ed has a 97 which has OBDII and can have the codes read with a scanguage.


Ed, just stop by any Autozone or similar parts store that will pull your code for free and tell you what's wrong. Of course, you probably knew that since you say you're a retired mechanic.


EDIT: CJF beat me to it. I'm a slow typer.

 

[SeanAndHis80]

A 97 will not have the two wires to short - you will need an OBDII scanner to determine the code. If you are near an AutoZone they will usually scan the code for you for free.

...and if we are just guessing I would say you have a P0401 code which is insufficient EGR gas flow. But hey, a guess is worthless without getting the code scanned.

 

[94SRUNNER]

Hi Ed, welcome.

I would suggest taking it to a autoparts place, such as Autozone and have them check codes via the diagnostic port on the drivers side fuse panel.

Good luck


Looks like I was late on this one

 

[Beowulf]

I'm a retired mechanic so I checked fluids and engine over pretty good and couldn't find anything wrong.
What is this light connected to and what might I check that I have overlooked.

You must have been retired a long time Ed!

Toyota calls that a Malfunction Indicator Lamp (MIL) and it is triggered by the Electronic Control Module (ECM) that is the electronic brains of your drive train. As others have told you, all 1996 and up vehicles imported into the US have On-Board Diagnostics ver 2 (OBD-II) which means a bunch of sensors are monitored by the OBD software in your ECM and if something is out of the specs as specified by EPA, the ECM will trigger the MIL.

As Sean alluded, the P0401 is a fairly common failure on the OBD-II trucks. Problem resolution has been covered here on 'Mud several dozen times... maybe a hundred or more times. Please do a search if this is the code you come up with.

If you have another code then it is quite likely it is one that we have helped with before and someone will give you pointers on how to resolve the issue. It is rare that someone gives us a code we haven't seen before.... but it does happen.

Good Luck and keep us posted.
-B-

 

[Ed Purmals]

Thanks guys. It has been about 20 yrs. since I left the mechanic trade so OBD stuff is new to me. I did get the code read and got a PO 141, which I believe is the 02 sensor, the one behind the cat.
Thanks again to all.

Ed

 

[Beowulf]

That would be a P0141. (Pea-zero-one-four-one). It is important to get this correct so this thread will come back when others do a SEARCH. Plus if you start looking this up on Google, you'll need to enter in the correct code.

First you should check the wiring but the later models don't usually have a problem with the O2 wiring because Mr T did a great job of keeping it up and out of the way. Earlier models, the harness was on one of the front control arms and could get messed up.

When you decide to replace the O2 sensor you will be much happier if you buy a Toyota part. Cruiserdan is an excellent source for genuine Toyota parts. My recommendation is to replace both O2 sensors at the same time if they are original 1997 parts. They are "wear" parts and they have the same time and miles and will wear at the same rate so if one fails, the other is not far behind unless it has been replaced before. (Not sure you'll be able to tell if it has or it hasn't.) FWIW, the front O2 sensor usually fails first.

-B-

 

[retrofive]

100% Percent agree with -B-. One thing to check on the 02's before replacing would be harness. I had the same code (but ODB I ver) and disconnected cleaned out and reconnected. Since then have'nt thrown the same code again. Not to say they don't need replacing eventually, or mine really do need to be replaced.... just my experience (very limited but).

 

[SeanAndHis80]

Just to add to the last two posts - the nuts that hold on the O2 sensors are one time use nuts. Some have reused them with success - but it is best to buy them new when replacing the sensor.

 

[Beowulf]

... the nuts that hold on the O2 sensors are one time use nuts.

I replaced the original O2 sensors (12 years and 177k miles) last month. You would cry if I posted pics of the nuts that I removed. They looked like new and if I had buffed them for a minute or two you wouldn't be able to tell which were 12 years old and which were new. Living in the desert is nice for trucks.

I installed new nuts because Dan made me buy them.

-B-

 

[Ed Purmals]

02 Sensor nuts?

I checked the connections for the 02 sensor and I still get the fault light. I looked at the nuts to remove the sensor and they almost look like they are welded on, or some kind of special nut. I tried to remove one and they seemed like the nut was going to strip or break, even though the threads on the stud look fine.
Any tips on removing them?
Where is a good source for a new sensor?

Thanks

ED

 

[Ed Purmals]

I looked at the 02 sensor nuts and they almost look like they are welded on? Any tips on getting them off, or just put the torque to them.

 

[Beowulf]

I looked at the 02 sensor nuts and they almost look like they are welded on? Any tips on getting them off, or just put the torque to them.

6pt socket. If this fails then a nut splitter. The best source for all your Toyota parts was given to you in post #9.

-B-

 

[TX Cruiser]

Sucks the light came back on. A lot of the time (haven't done a toy) disconnecting the battery cables, clamping them together and turning the ignition on clears everything, at least for some time, but sometimes for good. My bro did it with his 95 LC that has OBDII, but it ran like s*** for awhile, then the light came back on. Didn't much matter to him though, the guy at the inspection station didn't know the rules, failed him, then passed him when he showed him the statute.

 

[retrofive]

Sucks the light came back on. A lot of the time (haven't done a toy) disconnecting the battery cables, clamping them together and turning the ignition on clears everything, at least for some time, but sometimes for good. My bro did it with his 95 LC that has OBDII, but it ran like s*** for awhile, then the light came back on. Didn't much matter to him though, the guy at the inspection station didn't know the rules, failed him, then passed him when he showed him the statute.

?? huh.

Sure disconnecting the battery cables will "reset" the ECU, or you can just pull the fuse for a bit. Either way the ECU will have to re-learn and most likely run rough for awhile. Again either method clearing the code it will probably come back unless you actaully correct the issue.

EDIT: PS: My CEL was on at emissions too and pass 100%

 

[TX Cruiser]

You can do that too, but I recon most people don't have a clue where or which fuse it is, so I chose to pass along the method that even most unskilled motorist could use. Some electrical devices retain energy, that's why you turn the key on.

Not so on the light coming back on, it's just the opposite in my experience, which includes many different makes and models over several years. A bad tank of gas can trigger the light, and on some vehicles, it never turns off again.

I lied, I used the aforementioned method on an 03 Tundra the other day (forgot about that one), it didn't come back on and passed emissions testing. It didn't run like s***.

 

[Beowulf]

-B-

 

[33tab]

I would have to recommend the Scan Gauge II to remedy the reset of the CEL. It's the best purchase ever! Accurate temperature readings, speedo correction, reset the pesky PO401, etc...