P0120 CEL code

[garrett]

Hey guys... long time, no post

I've been having the P0120 code go on and off in my '98 for a couple weeks now. I've tested the connector and TPS sensor contacts per the FSM, and all seems to be within spec.

Harness connector voltage spec'd 4.5~5.5v, mine measured at 5v

Sensor connector resistance terminals 1-2 spec'd at 2.5-5.9 kohm, mine measured at 3.3
Terminals 1-3, throttle valve fully closed spec'd at 0.2-5.7 kohm, mine measured at 0.55
Terminals 1-3, throttle valve fully open spec'd at 2.0~10.2 kohm, mine measured at 2.6

So it would seem like my TPS passes, but maybe on the low side? I've got over 200k miles now (don't we all?) and I'm sure this sensor is original.

Other related factors, my cat converter was stolen ~10 months ago. It was replaced with a non-OEM converter, and I've read that the O2 sensors can throw this code as a result?

I just cleaned the TB and MAF tonight, and just recently replaced the air filter, so maybe it will sort itself out soon.

Any other thoughts/advice?

[MKtaco_98]

I also have a 98 tacoma 5vzfe and this happened to me 2 years ago. Do you have a K&N air filter? if so id swap it out for a paper I had one for 4 years and despite being cautious about spraying oil and letting it dry some still comes off the filter and gums up your intake. if you just cleaned the tb and maf clear the code and it should never come back on... if it does one of those two probably need to be replaced

[garrett]

Well just to update... not sure how it went away, but it did.

I cleaned TB/MAF a couple different times, and it didnt seem to help. The weather has changed drastically back and forth over the past couple weeks. Not sure if that has anything to do with it. I finally just ordered a new TPS and, of course, the next day, no code. So at least now I've got a spare TPS on hand. Although part of me wonders if the CEL just finally burned out, LOL.

And just for laughs... I had my 4Runner at the dealer for oil change/tire rotation and the 'service advisor' said they pulled the code and said i needed a new TPS. Unfortunately, its integrated to the TB so I'll have to replace the entire throttle body. LOL. I gave him the benefit of the doubt and assumed he just doesn't know anything... Really makes me sick to think anyone ever replaced the entire TB because of this code. I hope not.

[4x4mike]

Isn't the TPS integrated to the TB on the '01-'02? If so maybe they had their years mixed up.

[garrett]

Isn't the TPS integrated to the TB on the '01-'02? If so maybe they had their years mixed up.

Ah, that makes sense. I had no idea.

[4x4mike]

I might not have any idea either but for some reason I remember something like that.

[Seanz0rz]

The TB on 01-02 is throttle by wire, so my guess is it is a whole different sensor, and might just be sold as a whole TB. I'd have to look in the parts reference, but I'm kinda lazy and busy washing the truck.

Your CEL should self test when you start the truck, just to show the bulb is working.

You might want to actually test the range on the TPS. Should be a post about it here, if I remember later I will post the procedure.

[4x4mike]

As luck would have it I got a P0120 today. After some time with the Google it seems guys seem to throw $40 at a new TPS and will get another CEL within a few days. I've got a '99 so it's got a cable and the TPS is removeable and replaceable. Any ideas of what else I should check? It's the only code I threw.

Since Mojave I've cleaned the MAF, am running a Toyota paper filter and have a full tank of new fuel. It seems to drive fine but today I was doing some driving that isn't necessarily the norm. I ran SAG/Radio support for a 100 mile bike ride. Raining all day, some fast, some slow, lots of idling with steep grades up and down. No loss of power, change in idle speed or fuel mileage as far as I can tell.

[4x4mike]

Think this is legit?
http://www.amazon.com/Genuine-Toyota...ds=89452-35020



It's the cheapest I've found. Camelback, Toyota Part Zone and everywhere else want close to $50 after S&H.

This is the only review
"I'm Not sure if this is a true OEM TPS. But it says TOYOTA on the sensor and it comes in a box that says TOTOTA so it may be a real OEM TPS. It did however fix my Truck. And it is by far way less expensive to buy it here on on amazon for $25. I called the dealership and they wanted $70 and ebay is $45-$60 for an OEM TPS. You can get a cheap knock off TPS for around $20 but trust me and pay the extra $5 for an OEM TPS from here. Some Toyotas don't like aftermarket parts and it would be a waste of money to buy a part that doesn't work. Overall i am going to buy from this dealer again. I hope this helps."

Sounds like it's the sellers brother. The part sticker usually seals the Toyota boxes, right?

[Seanz0rz]

I'll send you a PM.

Basically, follow the FSM procedure for checking the TPS. You need a good scanner, but I recommend Torque Pro (android) and a bluetooth obd2 adapter.