Chrysler 300 Check Engine Light P0108 Fix - Manifold Absolute Pressure Sensor Circuit High

Last Updated on 2025-09-07

Seeing that check engine light pop up on your Chrysler 300 can be frustrating, especially when it’s throwing a P0108 code. This error points to a problem with the Manifold Absolute Pressure (MAP) sensor, which is reading higher voltage than expected. If left unchecked, this can lead to poor engine performance, bad fuel economy, and even starting issues. Let’s go through the steps to diagnose and fix this problem properly.

Understanding the P0108 Code

The P0108 trouble code means that the MAP sensor is sending a voltage signal that’s too high to the engine control module (ECM). Since the MAP sensor is responsible for measuring air pressure in the intake manifold, its readings are crucial for the ECM to calculate the correct air-fuel mixture. A faulty sensor or related issue can cause problems such as:

Poor fuel economy – The engine may run too rich, wasting fuel.
Hesitation or rough idling – You might notice an uneven idle or lack of power.
Hard starting – Incorrect pressure readings can make the engine difficult to start.
Engine misfires – The wrong air-fuel mix can cause combustion issues.

Ignoring this problem can also damage the catalytic converter over time, leading to expensive repairs.

Diagnosing the IssueBefore replacing any parts, a proper diagnosis is necessary. The first step is to connect an OBD2 scanner to the vehicle’s port, located under the dashboard near the driver's seat. With the ignition in the "Run" position (engine off), the scanner should retrieve any stored trouble codes. If P0108 is present, it is essential to check live sensor data. At idle, the MAP sensor voltage should be within the range of 1.0 to 1.5 volts. A voltage reading above 4.5 volts indicates a problem with the sensor or its wiring.After checking the sensor’s voltage, a visual inspection should be conducted. The MAP sensor is usually mounted on the intake manifold or throttle body. The wiring harness and connector should be checked for corrosion, damage, or loose pins. Vacuum leaks should also be considered, as a cracked or disconnected vacuum hose can cause inaccurate readings and trigger the code.

Finding the MAP Sensor

With the scanner pointing us to the P0108 code, our quest leads us to the MAP sensor, located cunningly on the side of the engine. A bit of exploratory surgery (removing the engine cover, that is) reveals our target. Here, it's essential to inspect not just the sensor but also its surrounding area for any signs of trouble like disconnected vacuum lines, which could be the culprits behind our errant code.

The Art of the Fix

Should your detective work uncover nothing visually amiss, you might consider employing a smoke machine to uncover any elusive leaks. If the sensor itself appears to have joined the choir invisible, fear not. Disconnecting and removing it is a straightforward affair, requiring a mere twist and a gentle pull. Installing the new sensor is just as simple, ensuring it's seated correctly before reattaching the connector and replacing the engine cover.

Confirming the Repair

After making the necessary repairs, clearing the code with an OBD2 scanner is the final step. The engine should be started and allowed to run for a few minutes. If the check engine light remains off and the car runs smoothly, the issue has been successfully addressed. If the light returns, further inspection may be required, including checking for additional vacuum leaks, wiring problems, or compatibility issues with the new sensor.

Final Thoughts

Fixing a P0108 code on a Chrysler 300 is usually a straightforward process. In most cases, the issue is related to a vacuum leak, dirty sensor, or faulty wiring. Proper diagnosis is key to avoiding unnecessary part replacements and preventing further damage to the vehicle’s engine components. Addressing the problem promptly can ensure the car continues to run efficiently and reliably.

For more DIY car repair guides, explore other resources on maintaining and repairing a Chrysler 300. Whether it’s replacing a MAP light bulb, fixing a third brake light, or repairing a window switch, staying informed and proactive can save time and money while keeping the vehicle in top condition.