i was driving home tonight and my check engine light turned on...

how do i go about running diagnostics to find out what is wrong?

is there a "flashing" code system that tells you a number on a corresponding chart?

any help is greatly appreciated.. i want to find out whats wrong and i hope it is not expensive..

 

Do you notice a diference in performance when the light turned on? If you have a aftermarket exhaust and had your cat taken out that could be the cause.

 

Heres a link to a site that shows how to get the check engine light to flash for a codehttp://www.4crawler.com/4x4/CheapTricks/index.shtml#CORelayLocation
and i think there is a link on that site that tells how to read the codes and what they mean.

 

ok i just figured out what it is.

code 21 is flashing. (flashes twice pause then once)
this is the main oxygen signal sensor

what does this mean? how do i go about fixing this?

 

probably your o2 sensor, call a parts store or a toyota dealership.

 

i have straight pipe with 40 series flowmasters.

it just turned on tonight though... ive been and the previous owner has been driving it with out the check engine light on....

21 might have something to do with the exhaust..

 

do i have to worry about the oxygen sensor if i have no cat?
and why is it only coming on now when it was fine before?

i remember in my honda i had 2 o2 sensors 1 before and 1 after and if they are reading the same thing (because there is no cat) then the check engine light will go on.

is it the same way in the these trucks?

 

If I were you I would disconnect the battery terminal to reset the computer and see if it comes back. If it turns back on you probably need a o2 sensor.... not really a big deal though, a open ended wrench and some liquid wrench is all you need to change it. You will see significant power gains if you change out a bad o2 sensor.

and do yourself a favor and buy a dealer or equivalent sensor, changing things twice sucks.

 

but do these trucks have 2 o2 sensors? (before and after the cat)

because i have no cat in my truck.. and its been this way for a while with no check engine light.

it could be because both sensors are getting the same reading.. (no cat)

but i'll try and disconnect the battery and see if it comes backk..

 

Yep....kinda supected exhaust. Same thing happend with my hardbody. It went off and on after I cut my cat out. I did replace the o2 sensor but the light still came on even after clearing the code a few times. should be ok as long as you dont mind seeing the light on.

 

well what i wanna know is if there 2 or 1 o2 sensors..

..::EDIT::..

i found out there is 2....
i dont know what to do now...

 

its probably came on because your exhaust finally burned the o2 sensor out. if i where you i would put a cat back in the exhaust. in my old jeep i cut the cat out and put a glasspack in its place and put a magnaflow on after that. ran fine for about 3 months then the light came on. put a new cat in and took the glasspack out and the light went off. you probably will have to replace the o2 sensors as well. i bought an o2 sensor for my old 03 camry and it was around $150 for one. easly fix though. took about 15 minutes. dont know what 2 would run for these trucks.

 

only California models have 2 o2 sensors. So I doubt it has 2 of them unless it was originally a California truck.

 

unhook the positive wire over night, that will reset the comp. see if there is any difference in performance. check for codes with the check eng light off. if it comes back is it the same trouble code?

where are the 2 sensors located? if one was after the cat it might need to be replaced with a heated o2 sensor. the cat will generate a bunch of heat, not having one will significantly lower temps to a O2 sensor after the cat.

 

so basically i have to change my o2 sensor?

i dont know if i want to put the cat back in.. that will cost about $80 to have it welded

 

yep. and you want to put the cat back in if you dont want to keep changing out o2 sensors.

 

no sense in replacing the o2 sensor if you have no cat.. it'll just burn up the new o2 sensor..

 

i did not say "change the O2" i said:

1. disconnect your battery overnight to reset the check light.

2. check for trouble codes in the morning b4 start

3. run... trouble codes? check light?

4. now this is important... where is the 2nd O2 sensor located?
IF its after the cat you can run a heated sensor insted OR make a new bung closer to the header for hotter exhaust to read.

i would also try looking @ http://www.pirate4x4.com/forum/forumdisplay.php?f=12

you can search that site easier through googles advanced search. i bet a lot of money that a fix is there or has been covered a few times, check the toyota faq

 

thanks for all your help!!

maybe just live with the CEL on for now?
i really dont want to put a cat back in.. to much hassle right now..

is it running rich and wasting gas? thats one of my concerns...

 

have you reset the light yet?


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