DTC P0641: 5-Volt Reference Circuit Out Of Range: Description

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The Powertrain Control Module (PCM) provides 5 volts to the following sensors:

The Engine Oil Pressure (EOP) sensor.
The Manifold Absolute Pressure (MAP) sensor.

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0641 sets.