Why are Check Engine, VSC Trac and Trac Off lights all on?

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The Check Engine, VSC Trac, and Trac Off lights are all on. Codes are P0420, C1201, C1223, C1256, and C1336. Vehicle seems to run fine. Just got it so don't know the history on it. Any help on where to start?

Visitor

in Springtown TX

Jul 26, 2018

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What are the best Toyota repair shops?

RepairPal Certified shops can diagnose and repair your 2003 Toyota 4Runner. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.

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What is your question?

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Why are Check Engine, VSC Trac and Trac Off lights all on?

What is your question?

Visitor

in Springtown TX

Jul 26, 2018

2 Replies

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pushrodon Jul 26, 2018

PO420 is indicative of a failed catalytic converter - as for the other codes you can find the definitions and detailed information @ https://www.engine-codes.com/ The other system (VSC) rely on proper engine operation to function properly - likely the reason for other lights.

davidv16on Nov 18, 2019

Clean the positive terminal. Take it off and put into vinegar for about 30 minutes and rinse and then use a wire brush to clean off as much corrosion as you can and it will fix the problem. Happened to me twice already. Don’t freak out. Just keep a bottle of vinegar and/or a wire brush in the car whenever the car does the same thing. I have an 05 Scion xB

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Swiftkillon May 17, 2019

Gas cap was loose, believe it or not. Tighten the gas cap AND disconnect the battery for 30 plus seconds. Reattache the battery and start the car. It worked like a charm, unless there is a deeper problem. I just did it after reading it on a forum here.

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Popular Answer

What are the best Toyota repair shops?

RepairPal Certified shops can diagnose and repair your 2003 Toyota 4Runner. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.