What Are The Symptoms Of A Bad Powertrain Control Module | RoadWeekly

A bad powertrain control module (PCM) can cause a wide variety of problems with your car. So, it’s really important to learn what are the symptoms of a bad powertrain control module.

If you’re experiencing any of the following symptoms, it may be time to have your PCM checked out: hesitation when accelerating, poor gas mileage, engine surging, and stalling. 

In some cases, a bad PCM can even result in a complete loss of power. So, if you’re having any trouble with your car’s performance, don’t hesitate to have the PCM checked out. It could save you money in the long run.

Common PCM Failure Symptoms

Let’s get to learn about the symptoms here.

Check Engine Light Will Be On

When your vehicle’s Check Engine Light turns on, this is often a sign that there is an issue with your vehicle’s PCM (powertrain control module), a key component in the engine management system. 

This can happen for a number of reasons, such as a loose or disconnected wiring connection, a defective sensor or actuator associated with the PCM, or even damage to the Powertrain system itself. 

Whatever the cause, it is important to have your vehicle diagnosed and repaired as soon as possible, as an underlying problem with the PCM can lead to more serious issues if left unaddressed. 

For example, if P1101 code chevy cruze is triggered due to mass airflow (MAF) sensor’s voltage problems, this could lead to damaged gears and other costly repairs down the road. 

So if you see your Check Engine Light On and suspect there may be an issue with your PCM, take action right away to get your vehicle inspected and assessed by a trusted mechanic. With timely diagnosis and care, you can avoid larger malfunctions and prevent more expensive repairs down the road.

Car Won’t Start or Will Start Roughly

When your car won’t start or starts roughly, it could be a sign of a PCM failure. PCM monitors all sensors and actuators related to the powertrain, and if it detects a problem, it will set a diagnostic trouble code (DTC) like 7e8

If the PCM fails, it will usually prevent the engine from starting. In other cases, it may cause the engine to start but run roughly. The 7EB Engine Code might also be seen.

Poor Gas Mileage

Loss of gas mileage is often seen as a symptom of PCM failure. This is because the PCM, or powertrain control module, is responsible for managing many important functions in your vehicle, including fuel delivery and engine performance. 

A faulty or failing PCM can cause mismatches between these systems, resulting not only in reduced fuel efficiency, but also causing damage to other parts of your vehicle. 

For this reason, if you notice a sudden and significant reduction in your gas mileage, it is likely that your PCM has experienced some kind of problem or issue.

Failure of Emissions Test

Failing the emissions test is often a symptom of a PCM failure. The PCM, or powertrain control module, is responsible for controlling the engine and transmission. 

It monitors various engine parameters and adjusts the fuel mixture and ignition timing accordingly. If the PCM fails, it can cause the engine to run too rich or too lean, resulting in increased emissions. 

In some cases, the PCM may also fail to properly control the transmission, causing the vehicle to fail the emissions test

Engine Stuttering or Stalling

An engine may stutter or stall as the result of a failure in the PCM, or powertrain control module. The PCM is responsible for regulating various aspects of engine operation, including air and fuel delivery, ignition timing, and idle speed. 

If any one of these systems experiences an issue, it can change how the engine performs, leading to such problems as sputtering or complete stalling. Such symptoms are caused by a loss in power or a change in fuel/air ratios. 

In particular, if the spark plugs or other components related to ignition are not working properly, this can cause erratic performance or full shutdown of the engine. Additionally, issues with the throttle can lead to inconsistent idling and difficult starting.

Erratic or Random Shifting

Erratic or random shifting may be a symptom of a PCM failure. When the PCM senses that these parameters are not being adhered to, it will switch into an erratic or random mode to compensate. This can result in skipping gears, jumping gears, or other unbehavioral patterns. 

In some cases, this phenomenon may actually be an indication of a larger issue with the transmission itself. Therefore, if you notice irregular shifting behavior in your vehicle, it is important to have your PCM tested and evaluated by a qualified mechanic as soon as possible. 

A PCM Related Trouble Code

Receiving a PCM related error code can confirm failure within your vehicle’s powertrain control module (PCM). So if you notice that you have received an error code associated with the PCM in your vehicle, make sure to take immediate action so that you can get back on the road quickly and safely.

What to Do When PCM Failure Symptoms Are There

What to Do When PCM Failure Symptoms Are There

If you are experiencing PCM failure symptoms, such as error codes or error messages on your dashboard, the first thing you should do is consult your owner’s manual for more information about what these symptoms may mean. 

It is also important to seek out help from a qualified mechanic who can assess the issue and provide potential solutions. 

For example, they may recommend running diagnostic tests to determine if there is a problem with your car’s computer system or electrical components. Additionally, they may be able to make adjustments or other minor repairs that will help get your car back up and running. 

Ultimately, taking action as soon as possible if you experience PCM failure symptoms will help reduce the risk of further damage and costly repair in future.

How the PCM Works

The powertrain control module, or PCM, is the central component that controls how a vehicle’s engine and transmission function. This sophisticated system continuously monitors a variety of inputs from various sensors, including speed, air intake, fuel composition, and more. 

Based on this data, the PCM then adjusts how the engine and transmission operate to ensure optimal performance under different conditions. For example, when driving up a steep hill or accelerating quickly, the PCM may need to adjust how much fuel is delivered to the engine in order to maintain proper speeds and shift points

PCM Replacement Cost

The cost of replacing a powertrain control module can vary depending on a number of factors, such as your vehicle type, the extent of damage to the module, and any required labor costs. 

However, in most cases, you can expect to pay somewhere between $800 and $1,500 for a powertrain control module replacement.

However, most of the money go to purchase the PCM model, while the labor cost is something between $75-100. 

PCM Reprogramming Cost

PCM reprogramming is a process that involves altering the programming of a PCM, or powertrain control module. This can be done either manually by an experienced technician, or via specialized software. 

The cost of PCM reprogramming depends on a number of factors, including the complexity of the programming required and the tools and equipment needed to complete the job. 

Typically, PCM reprogramming will cost you between $80 – $250, depending on these various factors. However, it is important to note that PCM reprogramming can offer many benefits for vehicle owners, including improved performance and efficiency, as well as enhanced fuel economy.

How Often Do Powertrain Control Modules Need Replacement?

It really depends on the vehicle and how it is driven. Some PCMs can last the lifetime of the vehicle, while others may only last a few years. 

Factors that can affect the lifespan of a PCM include: driving habits, environmental conditions, and the quality of the parts used in the PCM. In general, though, most PCMs will need to be replaced at some point during the life of the vehicle. 

The best way to determine when your PCM needs to be replaced is to consult your owner’s manual or take your vehicle to a trusted automotive specialist.

Can I Replace the Powertrain Control Module Myself?

While the powertrain control module is a critical component of your car, whether or not you can replace it yourself depends on several factors. One important consideration is your level of expertise and experience with car maintenance and repairs. 

If you have prior knowledge and training in this area, you may be comfortable performing the replacement yourself. On the other hand, if you lack the necessary skills and resources, it would be best to consult with an experienced mechanic or auto shop instead.


Symptoms of a bad powertrain control module can include hesitation when accelerating, loss of power, and even the Check Engine Light coming on. If you experience any of these symptoms, it’s important to have your vehicle checked out by a mechanic as soon as possible.

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