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.
DTC 99, App No. 2 (5-Volt Reference Fault): Notes
Accelerator Pedal Position (APP) module provides a voltage signal that changes relative to accelerator position. There are 3 sensors located within APP module that are scaled differently. DTC 99 will set when reference voltage on APP No. 2 is less than 4.8 volts for 2 seconds. When DTC 99 is set, PCM will light SERVICE THROTTLE SOON light and limit power.
- This step determines there is a good 5-volt reference.
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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.