A trouble code P0108: MAP Sensor Circuit High Voltage is one of 3 MAP sensor trouble codes that the fuel injection computer sets to let you know that the manifold absolute pressure (MAP) sensor has a problem.
In this tutorial I'll explain what this trouble code means. I'll also talk about some of the tests you can perform to find its cause and solution.
Contents of this tutorial:
You can find this tutorial in Spanish here: Código P0108 ¿Qué Significa? (1996-1997 2.7L Honda Accord) (at: autotecnico-online.com).
APPLIES TO: This tutorial, on the P0108 OBD II trouble code, applies to the following vehicles:
- 2.7L V6 Honda Accord: 1995, 1996, 1997
RELATED TROUBLE CODES:
- P0106 -What Does It Mean? (1996-1997 2.7L Honda Accord).
- P0107 -What Does It Mean? (1996-1997 2.7L Honda Accord).
What Does Trouble Code P0108 Mean?
In a nutshell, a P0108: MAP Sensor Circuit High Voltage trouble code is set by the fuel injection computer when it sees that the signal the MAP sensor is producing is stuck at a very high voltage value as the engine runs.
The normal voltage value the fuel injection computer should see is one that fluctuates as the engine intake manifold pressure changes due to changes in engine load.
Unfortunately, quite a few things can cause a P0108 trouble code, in the following headings I'll explain what some of them are.
Common Symptoms Of A P0108 Trouble Code
The manifold absolute pressure (MAP) sensor is an important component of the engine management system, when it fails, your Honda Accord's engine performance will suffer.
You'll see one or more of the following symptoms:
- Check engine light illuminated.
- Rough or low idle.
- Very high idle.
- Engine may start and stall.
- Little to no acceleration.
- Black smoke comes out of the tailpipe when the engine is running.
What Does The MAP Sensor Do?
The MAP sensor's job is to inform the fuel injection computer the intake manifold's vacuum pressure when the engine is running.
When the engine is idling and the throttle plate is closed, intake manifold pressure is high.
This high intake manifold pressure will cause the MAP sensor to produce a low voltage signal (usually around 2 Volts DC).
As you step on the accelerator pedal, the throttle plate opens and the engine accelerates. This causes a decrease in intake manifold vacuum pressure.
This low intake manifold pressure will cause the MAP sensor to produce a high voltage signal. At wide open throttle (like when you trying to run that red light), the MAP sensor produces a voltage around 4 Volts DC.
As long as the fuel injection computer sees the MAP sensor voltage signal decreasing/increasing, as you step on or off the accelerator pedal, it knows that the MAP sensor is functioning correctly.
What Causes A P0108 Trouble Code?
The most common cause of a P0108 trouble code is generally a bad MAP sensor that is no longer producing a voltage signal that decreases/increases with the changes in intake manifold vacuum, but not always.
Here are other common cause of a P0108 trouble code:
- The MAP sensor signal wire has a short-circuit to voltage problem.
- A bad MAP sensor connector causing an intermittent false connection.
- The MAP sensor's vacuum inlet is plugged.
- The MAP sensor's Ground wire has an open-circuit problem between the MAP sensor connector and the PCM connector.
- Bad fuel injection computer (although very rare).
- Major vacuum leak.
How To Diagnose And Repair A P0108 Trouble Code
Troubleshooting and resolving a P0108 involves testing the MAP sensor to see if its output signal is stuck in one high voltage value as vacuum is applied/released to it.
The MAP sensor test also involve making sure that it's getting 5 Volts and Ground from the fuel injection computer.
You can conclude that the MAP sensor is bad, and needs to be replaced, if your test results confirm:
- That the MAP sensor signal voltage DOES NOT decrease/increase as vacuum is applied/released to the sensor.
- That the MAP sensor is getting 5 Volts.
- That the MAP sensor is getting Ground.
You can find the MAP sensor test explained in detail here:
Where To Buy The MAP Sensor And Save
Avoid buying a cheap knock-off part to replace a bad MAP sensor on your 2.7L V6 Honda Accord. This type of MAP sensor will only last a few weeks and you're back to square one.
The following links will help you comparison shop for the MAP sensor of known automotive name brands:
More 2.7L V6 Honda Accord Tutorials
You can find a complete list of 2.7L V6 Honda Accord tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression (1995-1997 2.7L Honda Accord).
- How To Test The Head Gaskets (1995-1997 2.7L Honda Accord).
- P0420 -What Does It Mean? (1996-1997 2.7L Honda Accord).
- How To Test The Ignition System (1995-1997 2.7L Honda Accord).
If this info really saved the day, buy me a beer!