P0446 and P0120

[Kirk_B]

Currently in Guatemala driving south through Central America. I have had an intermittent P0446 check engine code come and go for the last month. Engine has been running fine with maybe 1mpg less than normal, but at idle after a long drive, it sounds like it stumbles a bit. I turn it off and back on and seems to be ok.

I just pulled codes again and now it also has a p0120.

I have limited resources while on the road right now. Anyone have suggestions on where I should start to troubleshoot?

 

[JustTroItIn]

I have never had to troubleshoot those codes, but I suspect they are two different issues. P0446 is an evap code. P0120 is a throttle position sensor code and I would guess the more likely contributor to your stumble. If you have a live data reader you may be able to see the TPS output.

 

[2TH4IST]

Visually check the evap hoses. Had a tacoma w/very small evap leak and it was the fuel cap seal had cracked and was not holding pressure. Also might want to check your charcoal canister for any cracks. If you have any you can repair with jb weld.

 

[Alyssa575]

For a P0446 code, I’d start with the EVAP vent control valve, since it’s the most common cause. Check for a stuck or failed valve and inspect the vent line for clogs or kinks.
Next, look at the charcoal canister for blockage or carbon debris, and inspect the wiring/connectors for corrosion, shorts, or opens.
If those check out, test the purge valve and fuel tank pressure sensor. ECM issues are rare and should be considered last.

 

[phattyduck]

Year and engine would help remote diagnosis...

P0446 on my 4Runner ('99 V6) was a crack around the bottom of the evap canister. I sealed mine with a bead of RTV to allow future minor movement in the plastic.

P0120 is a TPS code - you can keep going with this one as long as it doesn't cause drivability issues. Check for a 'smooth' resistance response from the TPS sensor. Replace with a quality part (low mileage used or OEM) when available.

-Charlie

 

[T4R2014]

That stumble is the TPS, you probably won't notice much from that P0446. If you have an 01+, new OEM throttle body and RIP your wallet. Pre 01 is about $70 if I remember correctly from a year ago when life was tariff free. Since you're in Guatemala I would just order from Partsouq either way.

 

[Kirk_B]

Year and engine would help remote diagnosis...

P0446 on my 4Runner ('99 V6) was a crack around the bottom of the evap canister. I sealed mine with a bead of RTV to allow future minor movement in the plastic.

P0120 is a TPS code - you can keep going with this one as long as it doesn't cause drivability issues. Check for a 'smooth' resistance response from the TPS sensor. Replace with a quality part (low mileage used or OEM) when available.

-Charlie

Oh yes, forgot that info; 1999 3.4L