1999 t4r sr5, 260k miles.

i've been having this problem with my CEL, the truck runs fine though, however couple months ago my CEL came on..it was on for a good month, then it went away..i had the CEL off for about 2 weeks, then it came back on. I went to autozone and the pissed off employee pulled codes and said it was my bank 1 sensor 1. i forgot the code number but it had a 3 a 0 and 1 in it i think. it came back on last month and stayed for couple weeks untill the other day it went away..the truck runs fine wheter the light is on or off..but im just worried what it is and what could happen. if its an 02 sensor..do they usually fix themself for a bit? b/c i have no clue why my CEL comes on for a month..goes away for couple weeks then comes back on.

also, i've noticed sometimes when im at a light, the truck will idle rough and rpms will drop below 500. there were 2 instances where the truck completely shut off. other than that it usually idles really rough.

ive had my spark plugs changed, fuel filter changed, ran some STP fuel injector clear 2x, cleaned my MAF sensor and TB, changed my air filter also. but i still get the rough idle at times.

any help would be good.thanks

 

Did you do wires with the plugs? P0301 would be a misfire for cylinder #1 if that's what the code was. O2 sensor code is usually P0420 IIRC.

I would get some new OEM wires if you haven't and then test the coil packs (you could swap the packs and see if the misfire moves to a different cylinder). P0301 = cyl. #1, P0302 = cyl. #2, etc..

Next time the CEL comes on, have someone with a good code reader or a shop pull the codes and post them.

 

P1130 = A/F Sensor Circuit Range/Performance Malfunction (Bank 1 Sensor 1)
That is your A/F sensor before your cat.
Sounds VERY similar to the problems I have been having.
I am also getting the P1130 as well as a P0171 and P0172, which are system too lean and system too rich.
Your post reminded me that I had gotten the CEL to come on and clear itself a short time later in the past.
My money is on the a/f sensor since mine had gone completely in the past. I had the stealer replace it like an idiot, but it solved the problem and the light stayed off and the truck ran great.
Are you getting rich exhaust stink?

 

brian, i have had someone pull the codes at autozone, however i remember the number 3, 0, and 1 in the code . i know for sure there was no 4 or 2 in the code. when i did my spark plugs i did them one by one, and as for misfire, wouldnt i hear some loud rattleling coming from my engine if i had a misfire? i always thought misfires would give u a loud clacking noise.

skid, which one is cheaper to replace the A/F sensor or 02 sensor? what exactly does the A/F sensor do? and in the past i do not recall replacing the A/F sensor or 02 sensor at all. as for the exhaust stink..it seems normal to me. no excessive smoke or anything either. gas mileage seems to be ok,maybe below average but the truck runs fine.

thanks guys

 

mine was my throttle position sensor. I cleared it so far so good. However I am going to change it out.

 

It's common for misfires to not be heard or felt especially if it's happening only here and there, but now I'm leaning toward what Skidpalace said - P1130 is probably the code they read at vatozone, and that would make more sense because they said it was "bank 1 sensor 1".

I was just thinking misfires cuz that would cause your CEL to go on and off and it also has a 0,3, and 1 in the code. Skidpalace's idea fits even better though.

 

On Cali. spec two-cat trucks, the front sensor is an A/F (air/fuel) sensor, that does the same thing as an O2, but with different technology. Federal trucks have O2 sensors in front. All have o2 sensors in the rear. A/f sensors cost more than O2 sensors, but you have no choice if you have Cali. truck. In '99, Cali. spec trucks were sold all over the country, you have to look at info plate under hood or count cats to be sure what you have.

A sensor can throw codes way before it changes exhaust smell. By then, you probably have ruined your cat, too, and should prepare for real pain. I would not spend a dime before I knew the exact code. However, if you have had the truck for 75K or more, you can safely figure front sensor needs a change soon anyway.

 

Oh please don't say that. I am still trying to figure mine out. I can't even imagine blowing a cat.

 

As what TheDurk said, the sensor plugged in front of the cats is the A/F and OF COURSE it is like twice the price of the O2 senor after the cats.
Cheapest I have seen is ~$130 at Amazon.com.

 

I didn't mean to scare you. But it is a possible consequence of a bad front oxygen/air fuel sensor if left unresolved for long enough and unburnt fuel ends up going into the cat due to a rich condition. A misfire code is even worse.

I suggest you find out for sure what code you have and verify if you are Cali. spec or not. Then you can easily take steps to resolve the problem. Truth is, it sounds as though you aren't sure if the code you have now is the same as the code you had a few months ago which you aren't sure what it was. Get it read and get the numbers and you'll get plenty of help.

 

Mine was the O2 sensor by the cat!!! It did the same thing on and off and they couldnt really figure out which one it was. It is very easy to replace just pre lube it first.

 

I had a chat with my uncle who owns a repair shop and although he is no Toyota master tech, he has access to all the diagnostic equipment.
Since bak3rme's and my issues seem possibly related, I don't mind posting that he ran the P1130 and the P0171/2 codes through his Identifix system and more or less confirmed that he would be replacing the A/F sensor if I brought my truck to his shop. This backed up my own suspicions based on my past experience with a blown a/f sensor and the dozens if not hundreds of posts I have read here and on t4r.org.
I went ahead and bought a Denso 234-9002 a/f sensor from Amazon for $124 as well as an Autel Maxiscan MS300 OBDII scanner for $23 so I don't have to bug the guys at Advance anymore. These items will be here on Wednesday or Thursday. I will post if the new sensor puts the CEL out for good.

 

how much is it to get your engine checked out? getting the codes from vip or autozone? i've got the CEL coming on and off at times. it runs fine, but it was bogging this morning. think it was just the cold and it wasnt running for few days. altho i let it sit for a good 6 mins after i started it up

 

Most auto parts stores will pull your codes for free. Nest time your light comes on, drop by and have them scan it.

 

I'm thinking that it may be the sensor before the cat. Bank 1 is a left side if I'm not mistaken

I personally have P0420 lights up when it moisture and then goes away after some time. In my case I think I have O2 sensor after the cat as I don't beleive P0420 have any relations to before cat sensor.

So if yours is not P0420 it looks like it is front sensor either AF or O2. BTW, can he replace AF with O2 on both sides?

 

thanks for the info guys, this really helps in a way
as for how long having the truck. ive had it for over 100k miles
its been properly maintained. i replaced the spark plugs about 2 months ago as i said in my post. i dont even remember replacing an o2 sensor so hopefully that is the problem since they last somewhere around 75k miles. i live in atlanta so thats wayy on the east coast. my parents bought the truck in 01 or 03 i believe. they bought it used..so im guessin its been on the east coast the whole time. (being when we bought it the 4r was only a couple years old). NAPA said the o2 sensor would cost me 114 bucks. if i do buy it i plan on doing it myself.

got a question though. for a bank 1 sensor 1 (behind the CAT?) do i have to replace 1 or 2 o2 sensors?

thanks again for all the help guys

 

Bank 1 Sensor 1 is in front of the cat(s).

If you have a Cali truck it is an A/F ratio sensor and if it is a 49 State you have an O2 sensor.

 

And just to clarify, if you have a front A/F sensor, you have to replace with the correct A/F sensor. The technologies are very different (current variation as opposed to voltage), and a normal O2 sensor will simply not work. Get the correct OEM Denso sensor for your application or get used to that pretty little yellow light.

 

ok to answer the title question the reason that the CE light comes on and off is that it is an intermittent issue and if it does not happen when the truck has been turned on and off 3 times the light goes out.

as for the rest if you do not go and get the correct code pulled then it is all speculation!!

Pulling codes at autozone is free because they want you to buy the part there.

On that note In Cali it is against the law for them to pull the codes with out being a licensed shop!!

 

thanks guys! gonna stop in tomorrow. Or should i wait for the next CEL light come on and go straight to the store? To be honest, i've never had someone check my truck and get the codes. so i'm still new at this.