1999 4Runner 3.4 liter, intermitently throws a check engine light with a PL-120 code. The truck runs fine. When the CEL comes on I reset it and it seems to be fine but in a week or so the CEL comes on again. Other than the intermittent CEL the truck runs fine and just passed smog.

Any ideas on what part/ sensor is going bad?

Thanks.

 

Your code is P0120 and there's plenty of info on that one.
Just do a quick search and you'll find copious amounts of reading material.

https://www.yotatech.com/search.php?searchid=4126832

 

I actually have searched quite a bit and cannot find anything about PL120.

 

At a quick glance, seems to have something to do with the TPS sensor.

PM me your E-Mail and I can send the FSM testing procedures in regards to PO120.

 

Sent, thanks.

By the way, its a PO120... not PL.

 

Just had the same problem on my 01. While it could be a hort in the TPS circuit, more than likely the TPS needs to be replaced.

You can get them for anything from around $40 online to $80 + locally (my experience). Not sure what the dealership gets for them.

 

Related FSM sent. Hopefully it will be of some help.

 

Thanks. After doing some research I believe it is the TPS which is a relatively inexpensive part. The vehicle only has ~90k on it but it is 8 years old so I guess I shouldnt be too surprised a potentiometer is wearing out.

 

I found it for $39. at Toyota of Dallas... toyotapartsales.com

There is no damage to any of the wire loom and its all 100% stock so I too am assuming its the TPS that is wearing out.

Thanks

 

figured it was better to bump a thread than make a new one...

My engine threw this code PO120 (and behaves as it should with a TPS malfunction), so I want to swap it out... but my question is: where is the TPS sensor in the 3rd gen? I searched but didn't see much, so can anyone give me an easy answer? Thanks

 

It is right on the side of your throttle body.
See attached pic.

 

it only takes like 5min to replace.

 

perfect... i appreciate it

 

Update to the thread...

I replaced the TPS with a new one which was very simple to do. I verified before removal and after re-installation that the TPS settings were the same with my Scangauge II (10 - 75), although there is no adjustment of this sensor for this year vehicle. The CEL has not appeared since and everything seems to be working fine. I would say time will tell as the CEL only came on very intermittently before, but I think this fix has solved the problem.

 

It also solved my idle problem.

 

i had this code to show up in my 98 4runner and it comes and goes like once a month...however, i never notice any difference in how the truck/engine actually perform...