17
Dec
P0420 4runner. I replaced both o2s and it went away for 5mounths and then it came back–I had it reset a few times and it would stay off for a few tanks of gas and it did shut off by itself at least twice. This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Simply put this means your car is adding more pollution into the air than its supposed to. Anyone have any suggestions.
I believe this is the 02 sensor before the cat. Shes still running fine but I wont pass smog here with this throwing a CEL. Outlet temp of cat 100 degrees hotter than the inlet. If any other codes are present they should be addressed first. Ive had my new to me 99 4Runner for less than a week and Ive got my first code. 2082018 P0420 TOYOTA Description The Engine Control Module monitors the switching frequency ratio of heated oxygen sensors 1 front O2 sensor and heated oxygen sensors 2 rear O2 sensorA three way catalyst converter Manifold with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2.
For most people the first sign that anything is wrong at all is the service engine soon light coming on.
P0420 code on a 2002 toyota 4runner - Toyota 1999 4Runner question. P0420 - Catalyst Efficiency Below Threshold Bank 1 message dor check engine light. Jump to Latest Follow 1 - 6 of 6 Posts. What else needs to be done. Do not overlook other codes that are paired along with P0420. I replaced both o2s and it went away for 5mounths and then it came back–I had it reset a few times and it would stay off for a few tanks of gas and it did shut off by itself at least twice.