120k miles. 2.0L engine. PO133 Error Code. I replaced the O2 sensor upstream of the pre-cat with an aftermarket O2 Sensor. No change. Then I swapped in a OEM O2 sensor. No change. Now what? Can the O2 sensor downstream of the pre-cat be having issues? Any help greatly appreciated. Thanks.

Scott

 

Did you clear the code from the computer after the install?

If you replaced the O2 sensor and you are still getting the code, the problem could be an exhaust leak, a leak in the air intake tract, bad wires to the O2 or a problem with the MAF. First check for exhaust leaks, then intake leaks. After that check the O2 wires and connector). Lastly, check the MAF.

 

Codes cleared after each oxygen sensor install. MAF cleaned and reinstalled. How would an exhaust system leak create a PO133 error code? Oxygen sensor wires checked out ok.

Scott

 

I'd check for exhaust leaks first and then CHECK them MAF. Cleaning the MAF doesn't help if the MAF is bad.

I've seen people clean MAF thinking it will help (a different code) and it doesn't but when they replaced the MAF, the problem was solved.
https://www.hyundaiforum.com/forum/s...ead.php?t=8375

 

Put the old sensor back in it (OEM), reflash the PCM for the #139 update, may have other unlisted jibberish in the update, it is for :

DESCRIPTION:

This bulletin provides information related to the ECM software update of some
TUCSON (JM) vehicles which experience a malfunction indicator lamp illuminated with
the ECM (Electronic Control Module) system-related DTC, P0111.

• P0111: Intake Air Temperature Sensor 1 Circuit Range/Performance

NOTE: There are no vehicle performance issues associated with this condition.


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BE AWARE that the 0133 is seen a lot on ACCENT with craked front pipe (exhaust leak) but usually shows as a post cat ox code on Elantra (Tucson 2.0 is same engine)