VSC TRAC/ VSC OFF & Check Engine Light on 2001 4Runner

We had the same problem with the O2 sensor in our Avalon. Fixed the O2 sensor and the VSC and Trac lights turned off.

My guess is that the throttle retarding function for the VSC/Trac uses the signal from the O2 sensor or air/fuel sensor when cutting fuel.

From reading other people's experience with the same problem, some people are saying the 02 sensor and some are saying the A/F Ratio sensor. Are these the same thing?

The air/fuel, or "A/F" sensor, and the O2 sensor basically perform the same function, which is to tell the vehicle engine computer whether the ratio of fuel to air is rich or lean. A/F sensors give a linear signal which tells the vehicle's engine electronic control unit, or ECU exactly what the air fuel ratio is, while O2 sensors just tell the ECU whether the ratio is rich or lean. I believe that Toyota uses A/F sensors in some vehicles with CA emissions and O2 sensors in vehicles with Federal emissions.

Thanks. I see that now. It's a California model. Also I notice that beginning in 2001, the rear oxygen sensor changed on the 4Runner from a flange type to a screw-in type.

You're welcome!

The change from flange mount to screw-in mounts for O2 sensors apparently varied from year to year and depending on model. I think the larger threaded area for the screw-in type made stripping threads less likely than on the 2 smaller studs for the flange mounts.

I had the air/fuel ratio sensor replaced today and all is well again. $153 + tax for the Denso 234-9002 which hopefully is pretty close to the Toyota OEM part since Denso is a Toyota company. The mechanic did not charge me any labor (well it's my brother-in-law's shop). It took the mechanic only about five minutes to change once the part arrived from the parts supplier (fortunately the bolts were not rusted). My brother-in-law showed me his box of old A/F sensors as he changes a lot of them and saves them because someone comes by and pays him for the old sensors because apparently they have enough platinum in them to make it worthwhile. As with most of these heated sensors, it's not the sensor part that goes bad, it's the resistive heating element. He had some of the Denso sensors in stock but they're so expensive that he doesn't stock a lot of them.

While he works on a lot of Toyotas and he goes to Toyota classes at the local college where Toyota has an auto-technology program, he was still surprised that the VSC lights come on at the same time the check engine light comes on with the P1135 code. You'd think that this would be mentioned somewhere in the manufacturer code listing but it isn't, at least not in the book he had.

Someone in a forum had mentioned that it was a good idea to change the rear oxygen sensor at the same time as the air/fuel ratio sensor, but the mechanic said to forget it, that the rear sensors rarely go bad unless the catalytic converter fails.

Amusingly, in a search for the Denso sensor, I found that Amazon had the best price, "

Ironically, my wife said that the check engine light, VSC, and TRAC lights came on in our Sequoia today. I got out my trusty OBD II code scanner and came up with P0051, which is heated O2 sensor heater control circuit low for bank 2 sensor 1, which is basically the same condition you had, but with an O2 sensor instead of A/F sensor.

I'll check the sensor out in the daylight.

Uh oh, it might be some sort of pandemic.

I think your post was the second complaint of the problem this week, and mine is the third...

I'm pretty sure that these failures are being caused by something Obama has done, but I'm trying to figure out the exact connection. Probably something related to Cash for Clunkers. Or maybe it's related to the health care proposals.

How much does a Toyota dealer charge in labor for an 02 sensor or air/fuel ratio sensor replacement?

Between plugging in the OBDII scanner, looking up the fault code, getting the car up on the lift, and swapping it out, took about 20 minutes. I'd think that they must charge at least an hour in labor charges plus the mark-up on the part. The shop I go to would have charged me by actual time at $40/half-hour if they had charged me labor.

nope, bush trojan horse set for 9/10. (he was kinda slow.....)

The amount the dealer or independent shop would charge for labor depends on their hourly rate and the flat rate book they use. My guess is hour.