P0108 MAP Sensor Code Explained (2002-2009 4.7L V8 Dodge Ram Pickup)

  • By: Abraham Torres-Arredondo
  • Created: 03 July 2025
  • Updated: 03 July 2025
  • Articl Id: 863
P0108 MAP Sensor Code Explained (2002, 2003, 2004, 2005, 2006, 2007 4.7L V8 Dodge Ram Pickup)

If your 2002–2009 4.7L Dodge Ram is throwing a P0108 MAP Sensor Voltage High trouble code, you're in the right place.

This DTC means the PCM is seeing a signal from the MAP sensor that's way too high —usually above 4.5 Volts— even though the engine isn't under full load.

Understanding what the PCM is seeing (and why) is key to figuring out if the MAP sensor is bad or if something else is tricking the computer.

In this article, I'll break down what the code really means, the symptoms it causes, what can trigger it, and whether you should replace the sensor or test it first.

I'll also link you to a complete step-by-step MAP sensor test you can do with a basic multimeter.

Contents of this tutorial:

APPLIES TO: This tutorial applies to the following vehicles:

  • 4.7L V8 Dodge Ram 1500 Pickup: 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009.

MAP SENSOR MULTIMETER TESTS:

MAP SENSOR WIRING DIAGRAMS:

OTHER MAP SENSOR TROUBLE CODES EXPLAINED:

What Does P0108 Really Mean?

If your 2002–2009 4.7L V8 Dodge Ram pickup has triggered a P0108 code, here's what your scan tool might show:

  • Generic OBD II Definition: P0108 – Manifold Absolute Pressure (MAP) Sensor Circuit High Input.
  • Factory Dodge Definition: P0108 – MAP Sensor Voltage Too High.

So, what does that really mean? The PCM is seeing a MAP sensor voltage that's way too high for the engine's current operating conditions —usually above 4.5 Volts.

Since this engine uses a speed-density fuel injection system, the PCM relies heavily on the MAP sensor to calculate engine load and adjust fuel delivery accordingly.

Under normal conditions, the MAP sensor produces a voltage signal that changes with intake manifold pressure. At idle (high vacuum), voltage is low. Under load (low vacuum), voltage rises.

  • By "under load", I mean situations where the engine is working harder —like accelerating, climbing a hill, towing a trailer, or even just stepping on the gas to merge onto the highway.

But when that voltage is stuck at the high end or spikes without reason, the PCM can't trust it and sets the P0108 MAP sensor voltage high code.

Knowing exactly what the PCM is seeing —a MAP signal that doesn't make sense— is a gold mine of info. It tells us what the computer is reacting to and gives us a solid starting point to when testing the sensor.

It's worth knowing what symptoms to expect when the PCM thinks the engine is working harder than it really is —in the next section, I'll break it down clearly.

Common Symptoms Of A Code P0108

When your 2002–2009 4.7L V8 Dodge Ram pickup sets a P0108 MAP sensor voltage high code, the PCM is receiving a signal that suggests the engine is under heavy load —even when it's not.

This can confuse the fuel and ignition strategy, leading to a variety of driveability issues. You might notice:

  • Engine running rich (strong fuel smell from the exhaust).
  • Hard starting or extended crank time.
  • Rough idle, especially when cold.
  • Decreased fuel economy.
  • Poor throttle response or sluggish acceleration.
  • Check engine light on (CEL).
  • Occasional engine stalling.

These symptoms can come and go —especially if the MAP sensor is failing intermittently, shorting internally, or if there's an electrical issue affecting the signal wire. In the next section, we'll dig into what really causes this code.

What Causes Code P0108?

Code P0108 sets when the PCM detects that the MAP (Manifold Absolute Pressure) sensor signal voltage is too high for the current engine operating conditions. Typically, this means the signal wire is stuck at or near 4.5 to 5 Volts —a reading that normally only happens during wide open throttle.

This incorrect signal causes the PCM to think the engine is under heavy load all the time, which disrupts fuel delivery and ignition timing.

Here are the most common causes of a P0108 code on a 2002–2009 4.7L V8 Dodge Ram pickup:

  • Faulty MAP sensor: Internal short or sensor failure keeping voltage output high.
  • Signal wire shorted to the 5 Volt reference circuit or to battery voltage.
  • Wiring harness damage or connector issues, especially near the MAP sensor plug.
  • Oil contamination inside the MAP sensor's vacuum port due to engine blow-by.
  • PCM internal fault (rare, but possible).

Now comes the big question —should you just replace the MAP sensor and hope for the best, or should you test it first and know for sure? That's what we'll tackle next, so you can make the right call for your situation.

Should You Replace The MAP Sensor?

It's tempting to just replace the MAP sensor when your 2002–2009 4.7L V8 Dodge Ram sets a P0108 MAP sensor high voltage code.

Plenty of folks do —even some shops— and there's nothing wrong with this strategy. If the sensor is internally shorted and stuck at a high output, replacing it might solve the issue right away.

And if it doesn't? Well, now they know they'll have to dig a little deeper. Since the sensor isn't all that expensive, it ends up being part of the diagnostic process for many.

If you're leaning toward replacement, no shame in that. The sensor is easy to reach, affordable, and a new one will often clear the code —if the sensor's the real culprit. If that's the route you want to take, here are a couple of MAP sensors I recommend for your Dodge Ram (affiliate links):

2002-2003:

2004-2009:

When you buy through these links, you help support the site at no extra cost to you —and I truly appreciate that!

That said, I still recommend testing the sensor first. All you need is a basic multimeter and a few minutes to check its output voltage and confirm it's getting a solid 5 Volt supply and Ground.

Whether the problem lies in the wiring —like a short to power in the signal wire— or it's a faulty sensor, you'll know what to do next.

So, if you'd rather test it before spending money, you're in luck —I've put together a full step-by-step guide for both versions of the 4.7L engine. Check it out:

More 4.7L V8 Dodge Ram Pickup Diagnostic Tutorials

Need help figuring out what's going on with your 4.7L Dodge Ram pickup? This index brings together all my step-by-step tutorials in one place, so you can get to the root of the problem faster.

Here's a small sample of the step-by-step guides I've put together to help you out:

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