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Blown Pcm Fuse Symptoms : [ Detailed Guide 2022 ]

Blown Pcm Fuse Symptoms : [ Detailed Guide 2022 ]

The Electronic Control Module (ECM) of your car goes a long way in controlling the functions of the engine. At times, you might come across the term Powertrain Control Module (PCM) or Electronic Control Unit (ECU), both of which refer to the same module.

The function of the PCM fuse is to secure the computer of your car inside it. Unexpected surges in electricity can lead to damage to the computer. Therefore, the prime goal of the PCM fuse is to protect this valuable component of your car.

In case of a power surge, the fuse blows up, thereby mitigating damage to the device. Now, you might have different symptoms in case the PCM fuse in your car has blown up. Therefore, we have discussed these symptoms, that would give you a more holistic idea.

Blown PCM fuse symptoms

A blown PCM fuse can result in several issues with your car. It can make your vehicle non-functional. Besides, it would prevent the engine from starting, or lead to a non-functional battery.

The fuel consumption of your vehicle would also be higher than usual. Therefore, a blown PCM fuse can result in a number of technical glitches in your car.

1. Misfiring, stopping, or not starting of the engine

Inside the ECM, you have the fuse. When the PCM fuse blows off, it’s natural for the ECM to fail. So, you would find no power in the ECM when you try to start your car.

In case a fuse fails, it disconnects the power in the entire vehicle from the source. So, you would experience engine failure in the vehicle. Besides, the dashboard lights would also be absent in these situations.

The ECM is accountable for monitoring some important functions of the car, including ignition. This results in cranks and misfires in the engine.

So, it wouldn’t run smoothly. The defective computer system in your car also results in intermittent stalling and misfiring of the engine. These are erratic occurrences, and you can’t just predict the stalling or misfiring.

2. Flashing of the check engine light

The seamless functioning of all the electric parts in your car depends on the condition of the PCM. So, this encompasses the engine light too. When the fuse blows up, you might find the engine light showing up. This implies that the computer detects some errors in the sensors or circuits.

3. Poor mileage

In case the PCM fuse has blown out, it might result in a poor fuel economy in your car. In some situations, it might also show wrong readings. This happens when there is slight damage to the fuse, resulting in an inadequate flow of electricity to the ECM.

When the ECM fails, it would miscalculate the fuel requirement of the engine. Besides, the engine would calculate that it would need more fuel than it actually requires. Eventually, you would have adverse fuel economy in your car.

This can also cause a reduction of power in your car. Remember, if you have a blown PCM fuse in your car, all the symptoms might be similar to other technical glitches. Therefore, you need to carry out a physical diagnosis before trying to fix the issue.

What happens if PCM fuse is blown?

As we discussed earlier, a blown PCM fuse can lead to several issues in your car. You would experience a lack of power and poor mileage if the PCM fuse is not working.

Moreover, the dashboard would show the check engine light. So, you need to get the issue diagnosed. The most common symptom of a PCM fuse blowing off is engine misfiring. It might also stop or not start at times.

What should you do after detecting A Blown ECM Fuse?

Simply observing the symptoms might prevent you from fixing the problems with blown ECM fuses. The reason is, modern cars come with extremely complex systems.

The fuse has an impact on the ECM. This, in turn, controls the overall performance of your car. So, when you detect some symptoms of a blown-off ECM fuse, you need to consult a professional.

1. Check or replace the shorts

At times, there might be damage in the wire that connects the battery to the ECM. This might lead to a short circuit, or shorting, causing a sudden surge in power.

In case the surge is more powerful than the capacity of the fuse, it would blow. So, you need to check the wiring for short circuits. This can be an utterly painstaking pursuit. So, car owners need to consult a professional. They would use advanced devices to identify short circuits and solve the issue.

Experts would check the wiring in different parts of the car’s engine. These include the ECM, crankshaft sensor, fuel pump relay, ignition module, ignition coil, pump, and fuel injector.

Besides, you need to inspect the flooring wiring, finding whether or not they are wet. These issues can lead to short circuits around the engine.

2. Replacing damaged starter

In case there is a damaged starter in your vehicle, the energy from this component can get to the ECM.

This can blow the fuse in case the power surge is too strong. If your starter sustains damage, you would hear a clicking noise. So, you need to address this issue so that the fuse doesn’t blow off frequently.

3. Replace bad fuel pump

The fuel pump in your vehicle might sustain damage at times, in case it has overheating issues. This would lead to more amperage consumption.

When this crosses the capacity or limit of the fuse, it would blow up. So, you need to get the malfunctioning fuel pump replaced and get the issue sorted out.

4. Oxygen sensor positioning

When the wiring of the sensor comes in touch with the exhaust, it can lead to grounding. The fuse would instantly blow up when this grounding happens.

Is it expensive to replace blown PCM fuse?

Unfortunately, replacing the PCM fuse would be a costly affair when it blows up. So, you need to shell out anything between $800 to $2000 to get the fuse replaced. Besides, you need to fork out a service charge of around $100.

However, when the PCM fuse blows off, you need not replace it every time. The cost of the fuse significantly varies. You can get a fuse box for $500 or so. Replacing a fuse would be much cheaper for automobile owners.

How frequently should you service the ECM fuse?

Remember, short circuits can lead to faster battery drainages and blow the fuse off. So, check the wires once a week for shorts.

However, you need not inspect the fuse too often. In case you detect any issue with the performance of your vehicle, make sure to inspect the fuse. For instance, the car might not start instantly, or you might detect cranks. So, in these situations, you need to check the fuse.

To check the voltage and amperage, you should have a voltmeter and an ammeter ready all the time. Inspecting these elements on a monthly or weekly basis would be sufficient for your car.


Instances of PCM fuses blowing off in different vehicles are pretty common. However, you know the solution now, and would be able to do the needful.

Unlike a problematic ECM, this would not be an expensive repair. So, experts recommend taking adequate preventive measures to keep the parts of your car in proper functional conditions.