P0108 Code – Manifold Absolute Pressure/Barometric Pressure Circuit High

Meaning:

The P0108 code is triggered when the voltage in the MAP sensor is too high
When the PCM has detected that the voltage in the MAP sensor is too high, P0108 happens

The PCM has detected that the voltage in the MAP sensor is more than 5 volts or generally more than commanded under the prevailing circumstance.

Main Symptoms:

  • Check Engine Light comes on
  • Poor fuel economy
  • Engine fails to idle and may not start completely
  • Engine produces black smoke (visible at tailpipe)
  • Engine cranks for long
  • Erratic acceleration

Possible Causes:

  • Faulty MAP sensor
  • Open or short in signal circuit, 5volt reference circuit or ground circuit
  • Leak in vacuum system, especially in the engine or supply line to MAP sensor
  • PCM is defective (least likely but not unlikely)

Diagnostic Steps:

  • Use an advanced scanner to pull engine codes
  • With that scanner, take the reading of MAP sensor when engine is off but key is on. It should be similar or close to barometric pressure (BARO) reading
  • If the difference between the two readings is more than .5 then you’re looking at a faulty MAP sensor

Read More: Signs Of A Bad Starter