My car 2011

My car 2011 corolla have a problem that traction control light and engine light on same time. I went to work shop and mechanic reset, but again came after some kilometers drive. Now they saying want to do " Evap test". I want to know how can diagnose ? How much the cost to fix ?

First, find a better mechanic.
Erasing the codes to fix a problem is like unhooking EKG leads to fix a heart attack.
If the shop provided you the codes that they erased, we might be able to provide some information.


If the Check Engine light turns on for any reason, the traction control light will also turn on.

That’s because the traction control requires the engine to be functioning properly for it to work.

Find a shop that knows what they’re doing.



If the check engine and traction lights are on at the same time, as posted above, focus on what’s causing the check engine light first. If you post the diagnostic code(s) here (the ones the mechanic read out for you), you’ll get some more ideas what might be the problem.

I’m presuming one of the codes is for the evap system. That is part of the fuel system that prevnts gasoline fumes from escaping the fuel system and polluting the air. An evap system problem may, or may not affect drivability. But it must be working for a car to pass emissions testing. The way that system works, whenever you refill the gas tank the fumes (in the near empty gas tank) are routed by the computer opening and closing various valves, the fumes go into the charcoal canister, where the gasoline molecules stick the charcoal, and the cleaned air is expelled to the atmosphere. When you get back into your car and start driving the computer then routes the gasoline in the charcoal canister back into the engine (by opening and closing another set of valves, one of these is called the “purge valve”), this gasoline is then used to propel the car. When all that works, it is invisible to the driver. But when it doesn’t, the check engine light comes on. One common cause is a failed purge valve.

I had the same problem with my 2012 Corolla and it was an easy fix. Tighten your gas cap because fuel vapors are escaping into the atmosphere(large leak).Buy a cheap OBD2 scanner and erase the code/s hoping they won’t come back or you can drive until the trac on/off and CEL goes off but that may take a while.

1 Like

Inspect the gas cap’s rubber seal as well. If it appears ok, try cleaning the seal with soap and warm water, then apply a very thin film of Vaseline.

I hope you’re not telling him to put Vaseline on the rubber O-Ring, Vaseline eats rubber.

Silicone Grease would be better.


If the check engine light comes on but doesn’t stay on, our regular mechanic will clear the code and tell us to come back if it comes on again. He says sometimes there can be a momentary glitch that doesn’t represent a true problem. It sounds like the OP’s mechanic shares that POV.

Unless the programming has changed, my understanding and experience that if temporary glitch, the CEL will turn off.
I want to know the code rather than have them cleared without recording the code.
Now the OP has his CEL illuminated, but may be an entirely different problem.

True, SG would be better, but I’ve used a very thin film of Vaseline for that purpose on my Corolla, b/c Calif emissions testing requires that seal is holding pressure. Tested every 2 years, so I’ve applied Vaseline to it on the same frequency. A few times instead of Vaseline I used motor oil now I think about it. This car has the same gas cap as it originally came w/from the manufacturer 30 years ago, and no visible deterioration of the rubber o-ring.

Yes a code would be helpful and the two are related to one problem. It will need to be diagnosed before a cost can be given. These are typically not an expensive repair and it usually does not cause drivability problems (except the traction control not working). If you find a shop that is 2 or 3 weeks out on their schedule, use them. They are very busy for a reason.