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.
2004 Mazda B4000 Base, AutomaticFACTORY OEM SERVICE PROCEDURE
DTC B1601: Unprogrammed Encoded Ignition Key (Key Code Format OK)
NOTE:
- The PCM disables the engine for 20 seconds every time DTC B1601 is set. The ignition must remain in the RUN position for at least 20 seconds before an attempt is made to start the vehicle with any encoded ignition key. Check the PCM PID ANTISCAN for this unprogrammed key timeout status.
Factory Service Tools
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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.