P0107 is a relatively common OBD2 trouble code that can occur in the Mercury Grand Marquis. In plain English, it indicates that the voltage coming from the MAP sensor is below the normal operating range.
P0107 Definition: MAP Sensor – Circuit Low Input
It’s a generic code, so it has the same meaning for the Grand Marquis as it would any other vehicle.
Here’s the definition of P0107, provided with the understanding it can help make diagnosing it a little bit easier.
The MAP (Manifold Absolute Pressure) sensor records the pressure in the intake manifold and reports it to the ECM. It can also be referred to as the barometric pressure sensor as well. For this article, the terms are interchangeable.
Circuit Input Low
The MAP sensor sends the current intake pressure reading to your Grand Marquis’s ECM in the form of a voltage signal. When the signal is below the normal operating threshold, P0107 will be stored, and the check engine light will come on.
P0107 Symptoms: Mercury Grand Marquis
With the MAP sensor not sending a proper signal back to the ECM, your Grand Marquis will probably not run very well: Here are some of the most common symptoms of P0107 you could be observing:
Mercury Grand Marquis P0107 Causes + Diagnosis
Here are the most common causes associated with P0107 and a proper order to check them in. Your first impulse may be to throw a new MAP sensor into your Grand Marquis and be done with it. And, if you have the money to throw at the problem, you may very well get lucky.
If you don’t want to make an unnecessary purchase, we’ll go over how to diagnose and test the MAP sensor before you replace it.
Before testing the MAP sensor, do a quick inspection of your Mercury Grand Marquis’s wiring harness. Then, follow the connection from the MAP sensor to where it meets the rest of the harness.
If the wiring is brittle, cracked, exposed, or damaged in any other way, repairing it will likely clear P0107. Also, examine the pins where the MAP sensor plugs into the wiring harness.
Test The MAP Sensor Voltage
Here’s how to go about testing a MAP sensor with a multimeter. You are trying to determine if the voltage going to the MAP sensor is correct and that the voltage leaving it is within range.
If the voltage is OK going to it, but too low coming out, that indicates a bad MAP sensor is causing P0107. If the voltage is lower than 12 volts, that could be a wiring issue.
This video from Ratchets and Wrenches covers exactly how to test the MAP with the multimeter.
Other P0107 Causes
While a bad MAP sensor or wiring issues are far and away the most common reasons you’ll bump into P0107 in the Mercury Grand Marquis, there are other (less common) causes as well. Here they are:
- BAD ECM
- Bad ground wire
P0107 in the Grand Marquis is almost always fixed by replacing the MAP sensor or repairing the wiring harness.