How to Know If You Need a Jeep PCM Replacement

Jeeps are fun to drive. No matter the conditions of the road, you can access the remote areas on safari with a jeep. Travel on roads you never thought possible with a smooth running Jeep PCM. 

Sometimes, the powertrain control module faces problems. Knowing the right time to replace it might save you a heartache. Failure of the Jeep’s PCM can result in lousy fuel injection or use, rough vehicle shifts, and continuous wear of the different engine parts. 

The PCM is responsible for many small functions of the vehicle. They include but are not limited to fuel mix with air ratio, engine timing, anti-lock brake mechanisms, and sensors among other transmissions. 

JEep pcm Engine control Module
Example of an Engine Control Module

Identifying Jeep PCM failure 

Knowing the various indicators of a failing engine control unit helps identify the right time to make a replacement. The failure mostly results in poor performance for your vehicle, such as fuel inefficiencies. There is a need to carry out a diagnostic procedure for your Jeep to identify a faulty PCM. 

The symptoms are easier to pick out since the PCM controls almost every aspect of your car. The code scanner presents several codes indicating the main problem with your PCM. However, there are more straightforward ways to know that your PCM needs a replacement. They include:

The light diode for check engine keeps flashing 

Check engine light illuminate due to many problems. However, having it checked now rather than later might save on costs. 

Vehicles fail or roughly starts

A voltage overload is a significant cause for vehicles failing to start or starting roughly. The overload causes shots in the wiring harnesses and can burn the computer’s motherboard or interfere with the ECM’s optimal performance. 

Wrong fuel use by the vehicle can also cause start failure. Poor engine timing is another major cause indicating PCM failure and the need for replacement. Diagnosing the PCM problem early and having it fixed might save you from getting stranded at the parking lot or on the highway. 

Systematic loss of gas mileage 

PCM works with the engine control and transmission control module to control the fuel-air mix. At the same time, it indicates when to shift gears for the system allowing proper and efficient use of your gas. Any change in this functionality causes increased loss of gas per mileage. 

Other reasons saving you from a PCM replacement include poorly inflated tires. Tires with the recommended pressure save on gas. 

p0172 code Shop at flagship one inc for engine control module

Stalling or stuttering engine 

Stalling and stuttering indicate a huge mechanical challenge with your car, or the PCM is entirely down. The only way to solve this is to replace the PCM to solve engine timing. 

Vehicle randomly shifts 

Shifting gears is an essential part of a moving car. Failure in the process is not only dangerous to the vehicle (risks destruction) but also to the occupants.

A significant cause for random shifts is environmental factors such as moisture, causing rust or damaging the circuits within the PCM. Bad shifts require a professional mechanic. The prompt solution will save transmission from any damage while ensuring personal and vehicle safety when in use. 

Failure in emission tests 

The emission test aims to ensure the vehicle mixes fuel and air in the right proportions for movement while conserving the environment. The PCM ensures the ratio remains functioning, guaranteeing complete combustion of fuel. Failure in the process results in more carbon monoxide and other particles coming from a running engine. 

The emission test measures this output, and the increase in carbon monoxide indicates trouble or a failed Jeep ECM engine control module. Replacing the PCM is easier in comparison to purchasing a catalytic converter for the same purpose. 

PCM DTC codes keep appearing on the diagnostic device

A failing PCM sends error codes to your reader device, providing you with the problem. Each code indicates a different issue and is easier to identify and address. 

The challenge is, not many people have a reader, and it takes time before taking the vehicle for a check-up. Therefore, take your car to the mechanic for regular check-ups and diagnostic processes. It will save you the cost and struggle of replacing worn out parts in case of a PCM failure or you can just get in touch with us for a quote regarding a jeep pcm ecm ecu repair. 

Flagship one LOGO p0172 code


Identifying PCM failure symptoms does not indicate PCM failure. They show a problem requiring a solution. A faulty sensor or a shorted wire are diagnostics that are easy to remedy. However, failing to correct them can cause the motherboard of your car’s computer to burn or explode, causing further damage. 

Therefore, look into the challenges the PCM indicates. Evaluate each at length and decide on whether to replace the PCM or not. Seek professional advice on the subject before committing to changing the PCM. Chances are your circuit board is fried but no way to tell without opening the jeep engine computer


What are the symptoms of a bad PCM?

These are of a wide range, starting with a vehicle failing to start. If the check engine light keeps flashing, the battery dies all of a sudden due to a leak, low gas mileage than prior, error codes appearing on your diagnostic tool, among others. 

How do I test a Jeep PCM?

Take your jeep to an experienced mechanic and allow him to have a look. Use a diagnostic tool to connect to your PCM to identify where the problem is and decode any error codes appearing on the device. 

Will a bad PCM drain battery?

Yes, it will. Any voltage overload or short can result in powering a car’s computer even when the vehicle is off. It causes a continuous drain on your battery, and after a while, the battery dies. 

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