Reading a high voltage MAP sensor code

Maintenance/Repairs
1

Vehicle: 2010 Subaru Impreza 2.5i

Recently I got a p0108 code which is map sensor high voltage. I tested the pressure of the MAP and at WOT it is 30 (barometric pressure) and at idle it’s 10ish which is normal. My computer doesn’t appear to have an option to test voltage. What could be wrong? I’ve cleaned it with map cleaner and made sure all of the wires and hoses are intact. From what I’ve seen, my map sensor is working properly but this code keeps appearing.

2

All that typing and not one word about the vehicle they’re talking about. :pleading_face:

Tester

3

My vehicle is a 2010 Subaru Impreza 2.5i

4

Voltage out of range - too high could mean than the ground came disconnected if it is a 3 wire sensor, which I believe it is. A wiring diagram would tell for sure. So the sensor Voltage is at maximum all the time. It could be a fault in the sensor too. The output could be shorted to the input Voltage.

The ECU has disabled the sensor and is using alternate fuel maps.

1 Like
5

Tester

1 Like
6

I see. I am trying to find a diagram for my vehicle that would show where the ground wire leads to. Do you know where I could find such diagram?

7

The sensor ground circuit is connected to the PCM and shared with other sensors.

8

I would start with a new MAP sensor. You could measure the Voltages on the wires too. I assume one is 0V and the other is 5V (inputs to the sensor), and the 3rd one is the signal output.

Diagrams can be found on random websites online. Partial diagrams are in repair manuals like Haynes or Chilton. Complete diagrams can be purchased from Mitchell at eautorepair.com

9

I presume you mean the intake manifold pressures are normal.

And the problem is MAP sensor output voltage isn’t corresponding to the measured pressure.

  • Make sure MAP connector is solidly connected to its wiring harness connector.
  • If that’s ok you’ll need that section of the car’s wiring diagram. There’s usually a precision voltage reference input to the MAP sensor. And the output is a voltage ranging from 0 volts to the reference input voltage, corresponding to the pressure. So make sure the reference voltage input to the map appears at the wiring harness pin. If that’s ok, you’ll have to figure out a way to measure the MAP’s output voltage (with it still plugged in). If the output voltage is ok, the problem must be somewhere between the MAP sensor and the engine computer. Maybe just a broken wire.

MAP sensors are pretty robust, no moving parts. Esp for a 2010. I doubt the MAP sensor is the problem unless you engaged in jump starting, which can damage any electronic part. I think these sensors have a diaphragm that could break/split but I 've never heard a report here of that happening. My guess, the connector isn’t making a good connection to the wiring harness. You may need to hire a shop so they can use their pro-level scan tool to monitor the MAP’s output voltage at the ECM…