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Check Engine Light Question

13K views 19 replies 6 participants last post by  sb5walker 
#1 ·
I have a 1995 Pickup, V-6, Auto, 4x4, extended cab.
There's 161400 miles on it, but it's in very good overall shape
My check engine light has been on for about a week and a half.
My truck runs fine. No noticeable difference in the way it runs.
Once in a while, the check engine light will go off, and it doesn't run so well, then the check engine light will come back on and it will run fine again.
I'm guessing that the computer goes into a pre-set program instead of real time analyzing when the check engine light is on. So there must be a sensor not functioning properly?
Like I said , it runs fine when the light is on.
Should I get this checked, or just drive it?
Any help would be appreciated.
Thanks
 
#4 ·
You don't need a scanner to read the code - you just need a paperclip to jump two terminals in the gray plastic check connector on the side of the fuse/relay block on the passenger inner fender. Instructions and the list of code meanings are in the fsm. If you don't have one, google 1993 toyota pickup service manual and look in the section ENGINE - MFI System--Diagnostics. Make sure you're in the 3VZE section which comes after the 22RE sections.

There are some instructions in this post, too:
http://www.toyotanation.com/forum/showpost.php?p=2659054&postcount=29

Sometimes the codes can be misleading - if you want, post 'em here & we'll pontificate. :D
.
 
#5 ·
You don't need a scanner to read the code - you just need a paperclip to jump two terminals in the gray plastic check connector on the side of the fuse/relay block on the passenger inner fender. Instructions and the list of code meanings are in the fsm. If you don't have one, google 1993 toyota pickup service manual and look in the section ENGINE - MFI System--Diagnostics. Make sure you're in the 3VZE section which comes after the 22RE sections.

There are some instructions in this post, too:
http://www.toyotanation.com/forum/showpost.php?p=2659054&postcount=29

Sometimes the codes can be misleading - if you want, post 'em here & we'll pontificate. :D
.
Thanks for the help.
I read the link that you included above.
I'm going to try the paper clip method.
Is there a link that shows which terminal is TE1 & E1?
Also a link that has the code meanings.
Thanks again for all the help.
 
#9 ·
i just crawled under the truck and found it is the o2 sensor before the cat, that is following the exhaust from the front to the back. it came apart where it goes into the flange or mount. And it looks like there is just a plug that you unplug and plug back in as far as the wiring goes.

Is that all there is to it?
Thanks
 
#10 ·
Yup. If you want it to run right, get a Denso. Best prices from rockauto.com. That should last you 90k miles.
 
#12 ·
Yes, the Denso has the OEM connector because it is the OEM part - the same that you would get from your Toyota dealer. With electrical parts, it pays to get the Densos because they are the factory parts and they are designed to work together. That includes the spark plugs, too: I've tried many different plugs in the 14 years I've owned my 3VZE and none work as well as the Denso K16R-U.

It's just as well to send the Bosch back - I've heard of people who have had trouble with them on Toyotas. BUT- if it was the right part, the connector should have fit. Be sure you're getting the front ("upstream") sensor for non-California trucks (assuming your truck was not originally sold in CA) - the California trucks have a second sensor behind the cat ("downstream"). Watch too, that you get the one for 4x4.

Once you've installed the new sensor, pull the EFI fuse in the fuse/relay box on the passenger inner fender (with ignition OFF) for 10 seconds or so to clear the codes from the computer and reset it. It will take a few drives and some miles for the computer to recalibrate with the new sensor.
 
#13 ·
Yes, the Denso has the OEM connector because it is the OEM part - the same that you would get from your Toyota dealer. With electrical parts, it pays to get the Densos because they are the factory parts and they are designed to work together. That includes the spark plugs, too: I've tried many different plugs in the 14 years I've owned my 3VZE and none work as well as the Denso K16R-U.

It's just as well to send the Bosch back - I've heard of people who have had trouble with them on Toyotas. BUT- if it was the right part, the connector should have fit. Be sure you're getting the front ("upstream") sensor for non-California trucks (assuming your truck was not originally sold in CA) - the California trucks have a second sensor behind the cat ("downstream"). Watch too, that you get the one for 4x4.

Once you've installed the new sensor, pull the EFI fuse in the fuse/relay box on the passenger inner fender (with ignition OFF) for 10 seconds or so to clear the codes from the computer and reset it. It will take a few drives and some miles for the computer to recalibrate with the new sensor.
Thanks for all the help!
The Bosch sensor's harness is a universal fit type. They do make a direct fit type. I don't know why the parts person didn't order that one? Anyways, I'm returning the Bosch and getting the Denso.
On my Truck, there's a sensor before the cat and after it. So it must be a California Truck? The sensor that needs to be replace is the one before the cat.
Here's a link to rockauto.com with the Denso O2 sensors.
http://www.rockauto.com/catalog/raframecatalog.php
It looks like I would need part#2344052.
Could someone verify this?
Also, what is the metric thread and size for the flange mounting nuts?
I know the ones on there are already rounded over.
Thanks again for all the help!
 
#14 ·
A good parts person is worth his or her weight in gold. Of course, the inverse is also true...

To give a link to the Rock Auto catalog, you have to use their older html catalog, instead of their new flashed based "interactive" one. You'll see a small link to the "traditional HTML catalog" at the bottom of the flash page:
http://www.rockauto.com/catalog/catalog.php

When you go in that way, you can get to the main page for your vehicle, which you can save as a bookmark. If yours is a Deluxe and not an SR5 this would be your main page:
http://www.rockauto.com/catalog/x,carcode,1278110

Part number 2344052 for the Denso sensor is what I come up with, too.

As far as the threads, I'm not sure. You might send a PM to "pickup" who recently replaced the nuts on his O2 sensor :eek: ; his is a 92 22RE but it's probably the same size:
http://www.toyotanation.com/forum/showthread.php?p=2651028#post2651028

As I mentioned to him, I recommend stainless nuts, and you might consider hitting the studs with a good rust converter, letting it fully cure, and then using a little bit of anti-seize compound (being VERY careful not to allow any of that to touch the sensor part of the sensor) - see my later post.

An alternative is just to get the nuts from a toyota dealer - they probably keep some on hand. I'm not sure if they would be stainless, but they'll fit.
 
#16 ·
Jayota, that is a GREAT lead - they have amazing prices, and I checked them out - the company name is Monarch Products, they've been in business since 1959, and the Better Business Bureau has NO complaints on file about them. They have an "A" rating.

Much appreciate!
 
#17 ·
I got my Denso sensor from Sparkplugs.com. $84.00 shipped.
I installed it yesterday. The nuts were tough to get off, even after soaking them with PB Blaster a few times. I had to purchase new nuts. I got stainless. I believe they were metric M8 1.25 pitch.
Everything else went pretty well and the check engine light is off.
Thanks to all of you for the great help!
It's very much apreciatted.
 
#18 ·
Congratulations on a successful diagnosis & fix. :clap:

It's helpful for us to hear the outcome, whether successful or not; of course it's even nicer when the outcome is a good one. Thanks for letting us know. :thumbsup:
 
#20 · (Edited)
The sub O2 sensor is the one in the back - downstream of the cat. Only the CA vehicles have them.

It sometimes happens when you replace the primary O2 sensor - the computer compares the front and back and can tell if the sub sensor is reading too lean. The code could also indicate a burned out heater circuit. Either way, yes, unfortunately, you'll need a new one.

The aggravating thing is that sub sensor doesn't do anything of value - theoretically it is supposed to verify the cat is functioning, but it doesn't even have a code for a bad cat!

They're expensive at sparkplugs.com, - $97, and the NGKs are $93, not much help. Amazon has had really good prices on Densos lately - I got the Denso part num for the back sensor from sparkplugs and searched for "denso" plus the part number on amazon and they have it for $77 including shipping:
http://www.amazon.com/Denso-234-4154-Oxygen-Sensor/dp/B000C5SG8G/

Since it's the back sensor and it doesn't do anything useful for you, you might try to clean it. Probably won't work, but might be worth a try. They're tough to clean because they get a coating of very hard carbon over the sensor and that's what keeps it from reading the exhaust. First make sure the heater circuit is okay - if it isn't, cleaning won't do any good. Test the resistance of the two wires that are the same color - that's the heater circuit. Should be 4.5 - 6 ohms at 73 degrees F.

The only cleaning method I've ever read about that has some evidence of working is to heat the end of the sensor with a torch until it's very hot - nearly glowing, and then plunge the tip into water. The sudden shock is supposed to cause the carbon to flake off. You may have to do it a few times, and try flushing the tip with a forceful spray of water. Do this in a clean bucket or bowl so you can see if any tan flakes have washed out. Since alcohol is a wetting agent, I would add a 1/2 pint or so of 90% isopropyl alcohol to the water. Can get that at a drug store.

When you reattach the sensor, make sure there are no leaks as that would cause the sensor to read lean - giving you the code again. Another thing that can help is to clean the pins in the connector - a lean reading is a low voltage reading, and the same thing can happen if there's some corrosion in the connector.

As before, remove the EFI fuse for a couple minutes after changing the sensor to reset the computer. (I said 10 seconds in an earlier post but a number of people have reported that it took longer for the computer to reset.)

If you tried cleaning your old sensor, test it by driving until the motor reaches operating temp, and then in a high gear, floor the gas pedal for at least 5 seconds or so. That's what will trigger the code if it is reading too lean.

Good luck - let us know how you make out.
 
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