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 31, Map Sensor, Open Or Shorted Circuit: Notes
MAP sensor responds to changes in manifold pressure (vacuum). MAP sensor consists of a semi-conductor type pressure converting element which converts a pressure change into an electrical change and an electrical circuit which amplifies and corrects electrical change. ECM applies 5 volts to MAP sensor.
Changes in pressure, engine load and RPM are converted into voltage input monitored by ECM. A low voltage input at ECM indicates low manifold pressure and a high voltage input at ECM indicates high manifold pressure.
Code 31 will set if voltage input at ECM indicates either very low or very high manifold pressure for at least .5 second.
- Checks for open or short to ground in Yellow wire between ECM and MAP sensor.
- Checks for open in Light Green/Red wire between ECM and MAP sensor.
- Checks for open in Brown wire between ECM and MAP sensor, and a faulty ECM or MAP sensor.
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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.
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