VSC and VSAC lights but NO check engine light.

I've got a 2003 SR5 V8 4wd. A few weeks ago I get the check engine light and the VSC and VSAC lights. I take it to Auto Zone to get the code read. It shows a faulty bank 2 sensor 1 O2 sensor. After another trip there because they sold me the wrong one, I replace it and unplug the battery to reset the code. The check engine has stayed off but the VSAC and VSC lights are still on. One thing I've noticed is that those two lights come on quicker than when the check engine light was coming on.

Any ideas as to what is wrong? I've taken it to Auto Zone but no codes are coming up.

Had the CEL and VSC lights come on yesterday.
Diagnosis from mechanic was:
O2 sensor bad
air flow mass sensor bad
leaky exhaust gasket
valve cover gasket leak
inlet manifold gasket leak.

sigh

Just had the same thing happen to my 07' T4R.

And the Verdict is:

Oxygen sensor in back of one of the cats. Tech showed me the code on their computer when he plugged it into my 4Runner.

This is how the tech explained (and showed me) how this works. 4Runner has 4 Oxygen sensors (1 on either side of each Cat). Engine side sensor monitors "dirty air", muffler side sensor monitors "clean air". If either sensor (or either side) fails, it throws the CEL. Makes sense to this point, right? On 2004+ models (and if you had the Sulfur TSB), if the CEL is lit, it also DISABLES the VSC/TRAC systems.



So I asked the question, why disable these systems if the CEL is lit? He said he did not have a direct answer but basically Toyota thought if the CEL light was on, any system that directly put a load on the engine that wasn't necessary should be disabled (which also means that the DAC might also not work) to prevent further damage to the engine. Since the VSC/TRAC works in conjunction with the brakes which can add a load to the engine, this system is disabled.

I asked one more question (for all you modification happy people who don't like VSC). Can I purposefully disable the VSC? No (officially). (unofficially you could throw a switch on the wire from one of the sensors to spoof the computer to think the sensor failed - since this would force a CEL condition, VSC would be disabled).[/QUOTE]

SEVERAL threads on this. buy a OEM gas cap install. remove battery cables. clean and put em back on.

Problem solved.

How about this instead?

Spend $150 or so and buy a decent scanner that can read OBD, SRS, and ABS codes and know exactly what the CELs are for and properly diagnose and repair the issues instead of a half assed solution of replacing a gas cap and pulling battery cables.

The $150 spent now will save countless dollars and hours having to avoid trips to Autozone to have a mouthbreather sexually assault your truck and sell you a Chinese IAC valve or 02 sensor, plus you can confidently diagnose (or at least start the diagnostic procedure) on your truck when lights pop up on the dash.

But what do I know?

I attempted the gas cap trick and to no avail, still had the codes. I had an idea that it wasn't that, as I could smell my exhaust and it definitely smelled a little off (rich).

Got the codes read and one of the O2 sensors was dead- which explains the rich smell. Replaced that and fixed a minor exhaust leak that was found in the process. Everything is all good now.

Hey Guys,

Been reading through everyone's experience with the VSC light, check engine light, etc. coming on. Glad to hear I'm not the only one experiencing this. HOWEVER I think my problem might be a bit different.

I have an 07' 4Runner, and those lights ALL came on the other day on my way to work. After work I was on my way home, lights still on, and I stopped at a gas station. Come back out, and car WILL NOT start. It was making the clicking noise, so it was trying. Figured maybe the battery just needed a quick jump.

After getting jumped the car started fine, but then ALL of my lights started coming on. The RED battery flashed, the ABS light came on... literally all of them.

Eventually had to get the car towed to the nearest place, and they said my alternator was bad. I figured that made sense since the battery was NOT holding a charge, so I had them replace the alternator, make sure the battery was good, they checked around the engine, mentioned a small radiator leak but said that as long as i keep up on the coolant and make sure it doesn't get worse, I can wait until my next payday for repairs.

This morning I'm driving to work again and the VSC, TRAC, and Check Engine lights all came on again. I'm terrified right now that Something more serious is wrong, but hoping that it's just a simple thing that was caused by the alternator going bad originally, or the fact that the radiator has the small leak in it.

Literally can't afford any more right now because of the previous tow and alternator replacement.

CAN ANYONE OFFER SOME INSIGHT? or maybe give me some kind of an idea as to what this might be? Thank you!

get a new gas cap unhook the battery put the new one on hook up the battery see if that works. only OEM

Could it be something that simple you think? The Gas Cap seems to be functioning fine and is on nice and tight. I DID, however just notice when looking under the hood that the plastic cap to the coolant reservoir wasn't on all the way. Haven't had a chance to drive the car yet as I am at work, but could that possibly cause those lights to come on?

The thing which changed it for me was disconnecting and reconnecting the battery and adding the gas cap from Toyota.

Awesome. I'll keep that in mind. Thanks!

Take out the gas cap and lubricate the o ring with some teflon grease, then tighten it back up and after a few minutes or so of driving that should go away. Worked for me.

My so and I pulled out his radio, to do so of course entailed removing numerous wiring connections (HVAC, 4WD, Heated seats, etc...) we didn't have the wiring harness we needed and re-assembled. He told me the next day that his check engine light and trac and vsc lights were on. I didn't think about it and went and got the codes checked. Threw the following codes -
c1201 engine system malfunction
p0441 evap incorrect purge flow
p0455 evap grodd leak / no flow
p0456 evap very small leak

Anyway - I spent a copuple days googling it - read on the gas cap, etc. and put it on the back burner due to life..

We got the adaptor cable in for the USA SPEC radio interface and removed the wiring connections again... that project went smooth as butter.

My son txt me the next day and told me all the lights were off. I have NO IDEA how one relates to the other... sounds like a skit from a national lampoon's movie w/cousin Eddie.. but when we plugged in everything this time we must have done it right??? Anyway - everything's working and all good to go.

Did you resolve this issue? We replaced Alternator and power steering pump on Thursday and these lights came on Saturday...haven't tried zero point calibration, code reads bank 1 & 2 catalyst efficiency below normal.

My son came home in my truck (05 Limited 4WD) and said all these lights are on. Same problem. I had this issue before in my 03. Took my scanner and read codes PO441 and PO455. Then took the gas cap off, lubed the o-ring, put it back on. Then disconnected the negative terminal to the battery for 30 seconds, put it back on, re-read codes and there were no codes. Only then did I start it, and no lights. Drove it around and no lights.

It took all of 5 minutes. Maybe it doesn't work for you, but it should be the first thing you try unless you just enjoy wasting time and money.