The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The ECM receives this information as a signal voltage that will vary from about 1-1.5 volts at idle to 4-4.5 volts at wide open throttle. If the MAP sensor fails, the ECM will substitute a fixed MAP value and use the TPS to control fuel delivery.

Code 33 will set when voltage signal reading is too high for a time greater than 5 seconds and if the TPS voltage indicates throttle is closed (TPS less than 2 percent). Code 33 will also result if circuit No. 469 is open, or circuit No. 432 is shorted to voltage or to circuit No. 416. If circuit No. 469 is open there may also be a Code 23 set.

NOTE: Test numbers refer to test numbers on diagnostic chart.

This test confirms Code 33, and determines if the fault is the result of a hard failure or and intermittent condition.
This step simulates conditions for a Code 34. If the ECM recognizes and sets Code 34, low MAP signal, the ECM and circuits No. 416 and 432 are not at fault.

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.

Safety Warning

Code 33 - Map Sensor Signal Volt High: Notes

Use the Manual With the Right Hardware

When to See a Mechanic

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