Table of Contents
- What the problem usually means
- How the Subaru Forester push-button start system works
- Fast checks when the start button does nothing
- Most common causes of a Subaru Forester push button start not working
- Warning signs that help narrow the diagnosis
- What to inspect next if the problem keeps coming back
- When the starter itself may be the issue
- How to prevent future start problems
What the problem usually means
If your Subaru Forester push button start not working, the issue is often in one of three areas: the key fob, the brake or shift interlock inputs, or the vehicle’s 12-volt electrical system.
Because push-button ignition depends on multiple electronic confirmations before the engine will crank or start, a simple fault can block the entire process.
The good news is that many start failures are caused by low key fob battery voltage, a weak car battery, or a sensor signal the car cannot verify.
Understanding how Subaru’s smart key and immobilizer system work makes it easier to narrow down the cause without guessing.
Modern Forester models use a smart key system that communicates with the vehicle through radio frequency and proximity detection.
When you press the brake pedal and the START/STOP switch, the vehicle checks several conditions before allowing ignition.
- The key fob must be inside or very near the vehicle.
- The brake pedal switch must register that the pedal is pressed.
- The transmission must be in Park.
- The 12-volt battery must have enough voltage to power modules and relays.
- The immobilizer and engine control module must recognize an authorized key.
If any of those conditions fail, the engine may do nothing, click, crank slowly, or show a message such as key not detected or press brake to start.
Before replacing parts, perform a few simple checks.
These are the highest-probability fixes when a Subaru Forester push button start not working complaint appears suddenly.
Check the brake pedal input
Push-button start requires the brake pedal to be pressed firmly.
If the brake light switch is faulty or out of adjustment, the car may not recognize the brake input.
Try pressing the brake pedal with moderate, steady pressure and watch whether the brake lights illuminate.
No brake lights can point to a switch or fuse problem.
Move the shifter to Park
Ensure the transmission is fully in Park.
On some vehicles, a shifter that is not completely seated can prevent starting.
Shift to Neutral and back to Park, then try again.
If it starts in Neutral, the shift position switch may need inspection.
Try the spare key fob
A weak or failing key fob battery can stop the car from detecting the fob reliably.
If you have a spare key, test it.
If the spare works, replace the battery in the original fob and inspect the contacts for corrosion or damage.
Use the emergency key-fob start method
Many Subaru smart key systems can still detect the fob when it is held directly against the START/STOP button area.
This is useful when the fob battery is weak.
If the vehicle starts this way, the issue is likely the fob battery rather than the car’s ignition hardware.
Weak 12-volt battery
A low or failing 12-volt battery is one of the most common causes of no-start symptoms in any modern Subaru.
Even if lights and accessories still work, the battery may not provide enough current for the smart key system, body control module, fuel pump prime, and starter relay logic.
Signs of a weak battery include dim interior lights, slow cranking, clicking sounds, or multiple warning lights.
Battery voltage that drops significantly under load can prevent the push-button system from completing its startup checks.
Dead key fob battery
The key fob battery is small, but it is essential for proximity detection.
If the battery is weak, the vehicle may not consistently find the fob, especially in cold weather or when the fob is inside a bag or near other electronics.
Replacing the fob battery is inexpensive and often solves intermittent starting issues.
Brake light switch failure
The brake switch is a critical input for push-button start.
If the switch fails, the vehicle may not know that the brake pedal is being pressed, so it will not authorize the engine start.
This issue often appears along with inoperative brake lights or inconsistent brake lamp behavior.
Keyless access or immobilizer communication fault
Subaru’s keyless access system relies on communication between the smart key, antenna modules, and immobilizer.
If a module loses power, has a connector issue, or sees interference, the system may display a no key detected message.
Problems can be intermittent and may happen more often in certain parking locations or when electronic devices are close to the key fob.
Blown fuse or relay problem
A blown fuse related to the starter circuit, brake lights, smart access module, or ignition system can stop the vehicle from starting.
Relays can also fail, especially if there was a previous clicking sound before the no-start condition.
Checking the owner’s manual fuse map helps identify the correct circuits.
Transmission range sensor issue
The transmission range sensor confirms whether the Forester is in Park or Neutral.
If the sensor reports the wrong position, the vehicle may refuse to start for safety reasons.
This often presents as an intermittent issue, especially if the vehicle starts after moving the shifter slightly.
Warning signs that help narrow the diagnosis
Different symptoms point to different failures.
Paying attention to what happens when you press the button can save time.
- No lights or response at all: often points to a dead 12-volt battery, bad connection, or main power issue.
- Lights come on but no crank: may indicate a brake switch, shifter, relay, or immobilizer problem.
- Clicking sound only: often suggests low battery voltage or a starter relay/starter issue.
- “Key not detected” message: commonly linked to the fob battery, antenna, or interference.
- Starts intermittently: may indicate a weak battery, marginal brake switch, or loose connection.
What to inspect next if the problem keeps coming back
If basic checks do not fix the issue, a more systematic inspection is the best approach.
Start with the 12-volt battery terminals.
Look for corrosion, looseness, or damaged cables.
A clean, tight connection is essential for stable module communication.
Next, inspect the brake lights and test the brake switch circuit.
If the rear lights are inconsistent, the switch may be failing.
Then check relevant fuses and relays in both fuse boxes.
Subaru models often separate interior and engine bay electrical distribution, so verify each circuit carefully.
If you have access to a scan tool that can read Subaru body and engine codes, check for stored diagnostic trouble codes in the body control module, immobilizer, or transmission system.
Codes can point directly to a failing switch, module, or communication issue.
When the starter itself may be the issue
Although the push-button system gets blamed often, the starter motor or starter relay can still fail.
If the vehicle has a healthy battery, recognizes the key fob, confirms the brake pedal, and shifts correctly but still will not crank, the starter circuit becomes a stronger suspect.
A single click or repeated relay chatter can indicate a starter relay, solenoid, or motor problem.
On some Forester models, a starter can begin failing intermittently before becoming completely inoperative.
Heat, moisture, and age can make the problem worse.
How to prevent future start problems
Routine maintenance reduces the chances of a push-button no-start situation.
Keep the 12-volt battery in good condition, replace the key fob battery before it fails completely, and make sure battery terminals stay clean and secure.
If the vehicle shows early signs such as slow starts or occasional key detection warnings, address them quickly before they turn into a complete no-start event.
- Test the car battery regularly, especially before winter.
- Replace key fob batteries at the first sign of weak detection.
- Keep spare keys available for quick comparison testing.
- Watch for brake light issues and fix them promptly.
- Have intermittent electrical faults scanned before they worsen.
If your Subaru Forester push button start not working issue appears suddenly, begin with the key fob, brake input, and 12-volt battery.
Those three checks solve a large share of the cases and quickly separate simple fixes from deeper electrical faults.