2002 Toyota Sienna-Engine light on

I changed ALL three catalytic converters, but engine light it on. I live in Cali, so, I need to pass smog. Of course, you won’t pass with engine light on. I was told, CHANGE ALL SENSORS. It’s four. We have change all except one, because they are having a difficult time getting off the sensor on there. Anyone with any suggestions. So the O2’s were all changed. The one, they are having difficulties changing is the one that goes on the biggest CAT. They rented tools, still can’t get off. Engine light did go off for a time, so they know, they need to get this sensor on.

Stop guessing what the problem and get the codes read. Should tell you exactly what sensor is giving the wrong single.

We didn’t guess, the codes were for two sensors, MAF and another. An emissions tech said to change all sensors because when changing the CATS, all sensors need to be replaced. I other code was for the CATS, BUT they were ALLLLLLLL replaced.