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john, The Car Guy
Category: Toyota
Satisfied Customers: 16285
Experience:  ase tech over 15 years in the field
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I have a 2002 Toyota Sienna and the check engine light, VSC,

Resolved Question:

I have a 2002 Toyota Sienna and the check engine light, VSC, and Trac Control light have all come on. The vehicle runs fine and complete regular maintenance. These lights also seem to go off periodically and then come back on.

Various web site responses have indicated these lights have also been a problem for other owners.

What should I do?

Ron Pasch
Submitted: 7 years ago.
Category: Toyota
Expert:  john replied 7 years ago.

The check engine light comes on when the on-board computer detects a fault in engine driveability or performance, transmission control system or transmission, or the emissions system, and a fault code is set and stored in the computer. Faults that can set the check engine light can range from a vaccuum leak, engine mis-fire, low engine compression, faulty sensor such as O2 sensor or other engine sensor, hydraulic pressure loss in transmission, transmission shift solenoid, open/short in wiring harness, emission evaporative system leak, or one of over a hundred different reasons.

The only way to know what set a fault code and turned the check engine light on is to have a diagnostic scanner hooked up to the on-board computer and read it for stored diagnostic fault codes. Many auto parts stores will do this service for free- check with you local parts stores. If none in your area do, then you will have to take it to a shop and pay to have the computer read for stored fault codes.

Without knowing the fault codes numbers, it would be irresponsible to guess as to the cause as there are hundreds of possible causes."
The abs a traction control lights need to be diagnosed the same way with a scanner or code reader that has abs capabilitys. The most common failure is wheelspeed sensors. The system should be scanned for trouble codes to help pinpoint or narrow down the issue
Customer: replied 7 years ago.


Many of the other web site entries on this topic refer to Toyota's poor record of these sensor lights actually providing any useful information to the owner. I appreciate your tip on checking with the local parts store for obtaining a free diagnositic check. It would seem Toyota has built a problem into is warning light systems just to increase useage of repair service centers.


If I can not get the free diagnostic check from a parts store, I don't like the idea of going to a dealership and paying $100 + just to tell me that the warning lights were false reads or, worse yet, the dealership fixes something that really doesn't need to be fixed or doesn't actually take care of the warning light problem. As you can tell by this response, I am very sceptical of auto repair services.


What do you suggest I do to determine that the auto repair service is doing what actually needs to be done to fix the problem?




Ron Pasch

Expert:  john replied 7 years ago.
well if you get me the diagnostic trouble codes i can help you narrow down the problems and give you labor times and parts costs to help you in determining if the shop is honest and not trying t o take advantage. Or maybe even guide you in repairing yourself. The first step is to get the trouble codes. If this was helpful please hit accept any further questions feel free to ask
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