Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code 46, Vehicle Anti-Theft System: Notes
Vehicle Anti-Theft System (VATS) is designed to disable vehicle operation if an incorrect ignition key or starting procedure is used. Anti-theft decoder module sends a signal to ECM if correct key is used. If proper signal does not reach ECM on circuit No. 229, ECM will not pulse injectors and vehicle will not start. Code 46 will set.
- If engine cranks and a Code 46 is stored, VATS decoder module, which generates signal to ECM, is not operating or circuit No. 229 is open or shorted to ground. If VATS decoder module is okay, ECM may be at fault; this is not likely.
- If Code 46 is stored and engine will not start, an anti-theft system problem exists or an incorrect ignition key or starting procedure is being used.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.