Subaru Impreza Push Button Start Not Working: What It Usually Means
If your Subaru Impreza push button start not working issue appears suddenly, the cause is often a simple battery, key fob, or brake-switch problem.
In other cases, the no-start condition points to a weak 12-volt battery, a failed starter relay, or a fault in the ignition immobilizer system.
Modern Subaru keyless entry and push-button ignition systems rely on multiple electronic checks before the engine will crank.
That means the real problem is not always the start button itself, which is why a structured diagnosis matters.
How Subaru Push Button Start Works
Subaru’s push-button ignition system uses a combination of the smart key, antenna receivers, body control modules, the brake pedal switch, and the starter circuit.
When you press the brake pedal and push the START/STOP button, the vehicle verifies that the smart key is authorized and that safety conditions are met before energizing the starter.
If any part of that chain fails, the car may show warning lights, keep the ignition in accessory mode, or do nothing at all.
Understanding the system helps narrow down whether the issue is electrical, mechanical, or related to the smart key signal.
Common Reasons a Subaru Impreza Push Button Start Is Not Working
Weak or dead 12-volt battery
The most common cause is a weak 12-volt battery.
Even if the dashboard lights come on, the battery may not have enough reserve power to support the body control module, fuel system, and starter relay at the same time.
Signs of a low battery include slow flashing interior lights, dim instrument lighting, clicking sounds, or a complete no-response condition when pressing the button.
Smart key fob battery is low
A weak coin-cell battery in the key fob can prevent the vehicle from recognizing the key from a normal distance.
The Impreza may still unlock with the mechanical or proximity functions in some cases, but the push-button start system may fail to authenticate the fob reliably.
Many Subaru models include a backup starting method that allows the fob to be placed near the START/STOP button or in a designated location for emergency recognition.
Brake pedal switch malfunction
The vehicle must detect the brake pedal before it will start.
If the brake light switch is faulty or misadjusted, the car may think the brake pedal is not being pressed, even when your foot is on it.
Another clue is brake lights that do not illuminate consistently.
Since the start system depends on this input, a brake-switch failure can mimic a key or starter problem.
Key fob not detected
Interference, a damaged key fob, or a dead fob battery can prevent the car from detecting the smart key.
Metal objects, aftermarket electronics, or a low RF signal can sometimes interfere with communication between the vehicle and the key.
If the display shows a key-not-detected message, the issue is usually in the fob, the vehicle antenna, or the receiver module rather than the starter motor.
Starter relay or starter motor issue
If the dashboard powers up normally but the engine does not crank, the starter relay or starter motor may be failing.
A worn starter can produce a single click, intermittent cranking, or no response at all.
On some vehicles, the relay may fail before the starter itself.
This is why diagnosis should include both the control side and the high-current circuit.
Blown fuse or electrical fault
A blown fuse in the starting, ignition, or body control circuit can disable the push-button system.
Corrosion, water intrusion, or damaged wiring can also interrupt communication between modules.
Electrical faults are more likely if the problem started after a battery replacement, jump-start, accident, or interior water leak.
First Checks to Perform When the Start Button Does Nothing
- Check whether the brake lights illuminate when the brake pedal is pressed.
- Look for key-not-detected messages or warning icons on the cluster.
- Try the spare key fob if available.
- Replace the key fob battery if it is old or unknown.
- Inspect the 12-volt battery terminals for corrosion or looseness.
- Try starting with the fob in the backup recognition position if your Impreza supports it.
If the vehicle has power but will not crank, the most useful early distinction is whether the issue is authentication-related or starter-circuit-related.
That simple split can save a lot of diagnostic time.
What the Symptoms Tell You
No lights, no response
This often points to a dead 12-volt battery, bad terminal connection, or major power distribution failure.
When the car shows no accessory power and no dash activity, the push-button issue is usually not isolated to the ignition system.
Lights on, but no crank
This usually suggests the vehicle is awake but not allowing engine start.
Common causes include a brake switch fault, key fob detection failure, starter relay issue, or immobilizer problem.
Clicking sound, but no engine rotation
Clicking commonly indicates the starter relay is engaging but the starter motor cannot turn the engine.
A weak battery can produce the same symptom because the starter needs high current to operate.
Engine cranks, but will not start
If the engine turns over but does not fire, the problem may not be the push-button system at all.
In that case, fuel delivery, ignition, crankshaft sensor input, or immobilizer authorization may be involved.
How to Test the Most Likely Causes
Test the 12-volt battery
Use a digital multimeter to check resting voltage.
A healthy fully charged battery typically reads around 12.6 volts, while significantly lower readings can indicate a weak battery or charging problem.
A load test is even better because it shows how the battery behaves under demand.
Check the key fob battery
Replace the coin-cell battery if it is old or if the vehicle has become less responsive over time.
Use the battery type specified by Subaru or printed inside the fob housing to avoid compatibility problems.
Verify the brake switch
Press the brake pedal and confirm the brake lights work every time.
If the lights are intermittent, the switch or pedal adjustment may need attention.
This is one of the most overlooked reasons a Subaru Impreza push button start not working problem appears.
Scan for diagnostic trouble codes
A professional scan tool can read body control, immobilizer, and engine control codes that are invisible to basic OBD-II readers.
Codes related to key authorization, brake input, starter relay control, or low voltage can point directly to the failed circuit.
Battery Replacement and Jump-Start Considerations
Jump-starting can help if the 12-volt battery is too weak to power the modules, but a jump-start is only a temporary test unless the battery and charging system are verified afterward.
If the battery has repeatedly gone flat, the alternator, parasitic draw, or battery itself may need inspection.
After battery replacement, some Subaru vehicles may need the system to relearn settings or reset modules.
If the problem began immediately after a battery change, inspect the terminal connection, battery type, and installation quality before replacing more parts.
When the Problem Is More Than the Start Button
Sometimes the start button is blamed when the actual issue is a network or control-module fault.
Subaru’s electronic architecture depends on communication between the smart key system, body control functions, immobilizer logic, and the starter circuit.
A fault in any of these can prevent starting without obvious mechanical symptoms.
Water intrusion, damaged wiring harnesses, aftermarket remote-start installations, or previous collision repair can all interfere with normal operation.
These cases often require advanced diagnostics rather than simple parts replacement.
When to Call a Mechanic
If battery and fob checks do not solve the issue, the next step is usually professional diagnosis.
A technician can test voltage drop, starter relay output, brake switch operation, immobilizer communication, and network codes in one session.
Seek repair help sooner if the vehicle is completely unresponsive, the issue is intermittent, or you notice burning smells, melted wiring, repeated fuse failures, or dash warning lights that return after a reset.
Common Fixes That Often Solve the Issue
- Replace the 12-volt battery.
- Install a new key fob battery.
- Repair or replace the brake light switch.
- Clean and tighten battery terminals.
- Replace a failed starter relay.
- Repair damaged wiring or corroded connectors.
- Address immobilizer or smart-key faults with a scan tool.
For many owners, the solution ends up being one of these basic electrical fixes rather than a major component replacement.
The key is to test in order, starting with the simplest and most common failure points.
How to Prevent Future Start Problems
Preventive maintenance can reduce the odds of another no-start event.
Keep the 12-volt battery in good condition, replace the fob battery before it becomes weak, and pay attention to brake-light behavior and warning messages.
If you notice slow starting or occasional key detection problems, diagnose them early before they leave you stranded.
Regular battery testing, clean terminals, and prompt attention to electrical warnings are especially important on modern Subaru models because the start system depends on consistent voltage and reliable module communication.