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symptoms of a bad ecm

Check Engine Light Turns On

The car’s check engine light is an indicator if there’s a problem with your car but if the engine light is always on and your car is doing just fine you may have a problem with your car’s ECM. You should see a mechanic to have your computer checked just to be sure everything in your car is doing okay.

Engine Stalling or Misfiring

One of the most common and noticable ECM problem is engine’s lack of power to accelarate or shaking and difficulty in changing gears. It may not always be the case but it is one thing to look out for since usually misfires turns on the engine light but you know your engine is in good condition. You can also notice that when your car is idle you can feel more vibration and the engine runs unevenly. Have your mechanic check your car to get the right daignosis as to why your car engine is stalling or misfiring.

Engine Performance Issues

ECM problems can also cause your engine’s performance since it controls mostly your car’s operation, It can affect the power of the accelaration of your enginge, fuel consumption and will also cause misfires. This will greatly affect your spending on you gas fuel and is very inconvinient when changing gears.

Car Not Starting

Sometimes when your car is having issues when you try to start it up or you’re having difficulty just to turn your engine on, it could be a faulty ECM since it handles almost all the operation in your car and the computer system might not be functioning well that causes the engine management to fail. There could be a lot of reasons why your car wont start up aside from your ECM, so it is best to have a mechaninc check your car to diagnose the main reason as to why your car wont start up.

Poor Fuel Economy

When you notice that you’re paying more money for gas with the same milage, your car’s accelaration power is not like it used to be and most specially your having difficulty in shifting gears. It could be a faulty ECM and you would want to have your computer checked, it is more cost effecient that paying more on gas.

Your Engine shuts off for no reason

When your engine shuts off suddenly, it could possibly be a failing ECM. The ECM protects the transmission unit allowing the vehicle to perform smoothly, so when the car reduces power, you might need to have it checked. On the other hand, the PCM acts as the brain of the vehicle, so when the fuel system doesn’t receive adequate fuel and air, the mixture will result in the car coughing or choking, or might totally stop running on its own.

Flooded Engine

In case your car gets submerged in water when crossing flooded roads, you may notice that your engine would start to malfunction and eventually stop running completely. This sounds like your engine control unit has been flooded and will need a replacement. The best thing to do at this point is to go to a mechanic to make sure that the ECU did not fail completely. Otherwise, your car is no longer safe for driving.

Increased Emissions

The Powertrain Control Module or PCM is the brain of the vehicle. It controls the emission system as well as the exhaust of the emission. If the PCM is faulty, it may fail the emission test and would often produce excessive colored smoke with fuel-like smell.

Transmission issues

Inconsistent performance in the transmission such as delay in shifting gears, sudden jacks, or having trouble starting the engine might suggest that there’s a malfunction around the transmission area. Since the ECM protects or holds the transmission control unit, you might want to consider checking the ECM when this happens. Typically, if your car’s transmission is showing issues, it will create a chain or reaction on the engine. You may also check other possible signs for these symptoms in the dashboard.

What makes an ecm fail?

The PCM is the most sensitive part of the car since it acts as the brain of your car and theres a lot of factors that can cause problems with your PCM. Some factors that can cause PCM issues are over-temperature and moist inside that can corrode your PCM. First thing you should do is to have it checked by a professional to diagnose the cause of the problem, almost always damages to the PCM requires replacement most specially if it’s a reman PCM.


It’s important to know what causes the vehicle to not work properly. One thing you can do is connect an onboard diagnostic tool to the diagnostic part so you’ll see if it will show the error codes indicating failure of the specific engine system. Other symptoms might be causing bigger problems. Make sure to have your vehicle checked by professionals. Catching the issues earlier could save the ECU and other parts and could still be repaired

Corrosion, moisture and solenoid damages

Exposure to several elements can cause errosion that can enter through the wiring harness and moistures could possibly damage the ECM. The fuel solinoid gets old and can get corroded as well due to continued exposure and aging. This is expected to happen when your ECM is around 5-10 years old.

Starter, battery, INJECTOR WIRING and grounding issues

Few clues that you can take note are the following: Engine misfiring or stalling, poor fuel economy, perfomance issue, vehicle suddenly stops or not starting at all Corrosion and damage due to moisture. You need to check the engine lights on the dashboard and the transmission control unit.