Subaru Forester won’t start – causes and how to fix it

Subaru Forester is a reliable road companion, but its a machine with hundreds of interconnected parts, and like any other machine it sometimes fail to deliver normal operation. In this article we will go through most common causes and how you can fix the problem.

Subaru Forester, Fifth Generation SK – (photo by Subaru)

If your Subaru Forester is facing starting problems, then it could be caused by something as simple as a dead battery or as complicated as a blown piston in the engine, but those are very rare.


The most common causes that hinders normal starting operation of your Subaru are dead key fob battery, dead 12v battery, corrosion on battery terminals, bad alternator, clogged fuel filter, broken starter, blown fuse, empty gas tank, immobilizer error or any fault in the electrical system.

Dead Battery

An expert car battery test should be carried out at the latest at the first signs of starting problems. Investigating more closely and doing a battery test will clarify whether the starting problem is clearly with the battery. A test can be used to measure the voltage between the battery poles, check the acid level and assess the condition of the starter battery.

If a new car battery has been installed, the battery may not yet reach its full capacity. There is nothing to worry about. A new battery only develops its full capacity over time. With original part quality, it can reliably start the car for many years without having to constantly check the capacity of the battery. But low-maintenance or maintenance-free is not to be understood as having an unlimited shelf life.

Testing 12v battery

Numerous motorists test their car batteries themselves. Here, the terminals of the testers are connected to the plus and minus poles as usual. They can also be used to measure voltage and power. There is nothing wrong with this type of battery test. However, the information obtained is not always clear. The result that follows is very simple and often imprecise. Especially with cheap variants that are supposed to test the battery quickly via the cigarette lighter, the result is sometimes vague or misleading information. Rather, such a test can be viewed as a guideline. You can only get a reliable test value with a high-current test. This test can be used to determine whether the battery can generate the required energy or not.

Testing battery with multimeter – a healthy battery should have between 12.3 to 12.9 volts

Tools such as a multimeter are needed to test the battery. The voltage of the battery can be measured precisely with the multimeter. Before the test, the multimeter is set to the voltage of the battery and connected to its plus and minus poles. Successful testing of the car battery, i.e. checking the voltage, usually results in values ​​of approx. 12 to 13 volts. Values ​​above 14 or below 11.5 volts require an expert assessment of the condition of the car battery. Because the battery may have a defect with these measured values ​​and must be replaced.

Corrosion on battery

Corrosion on the contacts of your car battery leads to loss of contact and reduced current flow, which means that your engine can no longer start properly.


To know if your car’s engine problems are from dirty battery contacts, you need to investigate them. If you lift the rubber covers over the two battery terminals, you can check the terminals for corrosion. If you discover white deposits or silvery-green deposits, but no further cracks or damage, you do not have to replace the battery, just clean it.

Corrosion on positive terminal of car battery

To clean the battery, you have to remove the pole cables first, which requires no special knowledge, just a little concentration, as the order is very important. First remove the black cable from the negative pole. If the pole clamp is very tight, you can open it with pliers. We advise against using metal pliers, but if you use them, you must make sure that you do not touch any other parts of the body. Next you can unplug the red positive pole cable. Once the battery has been removed from the circuit, you can start cleaning the corroded car battery. After cleaning, reconnect the terminals.

Dead key fob battery

What if the battery in the car key runs out? Can I still start my car? Yes, with an original key, the battery is only used to send the signal for vehicle locking. If the car key battery is empty, the door no longer opens or locks at the push of a button. The doors must then be opened manually. The immobilizer is controlled by a passive transponder. Passive means, among other things, that the transponder in the key does not need its own power source.

Key fob with dead battery should be in close proximity to push start button to start the vehicle – (Subaru Forester, fifth generation shown)

If you have a newer model of Forester which only has a key fob with push start and no place to insert a key. In that case, place your key fob as close to the push start button as you can and then start the car.

Broken starter – clicking sound

A starter motor is a motor for starting an engine. The average life of a starter motor is about 100,000 to 150,000 miles, and the life will be shortened if the engine is started more frequently. In any case, since the starter motor also has a limited life, it will break down after using the car for a long time, and if the starter motor breaks down, the engine will not start.

When you turn the key to start the engine, you will hear a clicking sound, which is the sound of a bad starter motor. And if the starter motor does not work with a healthy battery, suspect a malfunction of the starter motor.

Starter motor, Subaru Forester

If the starter motor fails, it usually needs to be replaced with a new starter motor. When replacing with a new starter motor, the cost is around $100-$200 depending on model year.

Temporary fix

If the engine does not start due to the starter motor, the engine may start if you turn the key while hitting the starter motor with something like a stick or metal tool. This workaround is effective when the parts inside the starter motor are stuck together or the gears are slightly out of alignment.

However, it is possible that the starter motor is nearing the end of its life, so it is recommended that you have it inspected at a dealer or maintenance shop.

Alternator failure

An alternator is a generator that produces electricity. If the alternator fails, it will not be able to produce electricity and the battery will not be able to charge. Therefore, even if you think that the cause of the engine not starting is a battery failure and replace the battery, the battery will soon run out and the engine will not start.

Alternators rarely break down. In particular, recent cars have improved performance, so it is said that they will last 200,000 to 300,000 miles. Still, it can break down depending on how you use it, and in the case of a used car, the alternator may be quite old. Don’t let your guard down.

If the alternator breaks down, it must be replaced with a new alternator.

Clogged fuel filter

The fuel filter does not wear out like a mechanical part, but it gets clogged by dirt and airborne particles and clogs over time . The permeability of the filter drops, and so does the fuel pressure. To a certain extent this doesn’t matter, but if the fuel filter is too dirty, the engine will no longer perform at full capacity and in some instance may not start at all. Cleaning is not possible, you can only change the filter.

Contact the author: benjaminsaunders@wheelsjoint.com



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