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 12, No Rpm Signal: Notes
ECM monitors crank angle and camshaft positions, and supplies .7 volt to crank angle and Camshaft Position (CMP) sensors. As signal rotor rotates, voltage is toggled high and low. ECM determines crank angle and camshaft positions by toggled voltage input.
Code 12 will set if ECM does not detect crank angle input while engine is cranking for 2 seconds or more, or ECM does not detect camshaft position input with engine speed 600-4000 RPM for 3 seconds or more.
- Checks for faults in crank angle input low circuitry and ECM.
- Checks for faults in crank angle input high circuitry and ECM.
- Checks for faults in camshaft position input low circuitry and ECM.
- Checks for faults in camshaft position input high circuitry and ECM. Also for a misadjusted signal rotor air gap.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.