# Key Fob Not Detected, Car Won't Start 2016 Toyota Scion iM

> ClearTheCode — Experiencing a 'Key Fob Not Detected Message, Car Won't Start' in your 2016 Toyota Scion iM? Learn common causes and quick fixes to get your vehicle running again.

Source: https://clearthecode.com/articles/key-fob-not-detected-start-car-toyota-scion-im-2016
Author: ClearTheCode

# Key Fob Not Detected Message, Car Won't Start 2016 Toyota Scion iM

Few things are as frustrating as getting into your 2016 Toyota Scion iM, pressing the start button, and being greeted with a "Key Fob Not Detected" message, preventing your car from starting. Even with the key fob clearly in the cabin, the vehicle's smart key system fails to recognize it, leaving you stranded. This common issue can stem from several sources, ranging from simple fixes to more complex electrical diagnostics.

## What drivers notice on this 2016 Toyota Scion iM

Drivers typically encounter this problem when attempting to start their vehicle. The primary symptom is the inability to engage the engine, accompanied by a specific message on the multi-information display. This isn't just an inconvenience; it's a complete lockout from operating your vehicle.

## At a glance: difficulty, repair cost, and diagnostic workflow

- **Difficulty Rating:** 6/10 — Moderate
- **Common Symptoms:** The engine does not crank or start when the push-button ignition is pressed.; A prominent "Key Fob Not Detected" message appears on the dashboard display.; The push-button start light may not illuminate green, or it might remain amber.; The steering wheel may remain locked, preventing any movement.
- **Estimated Repair Cost:** $100–$900 (parts + typical shop labor)
- **OEM Tooling Required:** Standard OBD-II scanner and hand tools

**Diagnostic workflow:**
1. Confirm the symptom on your vehicle.
2. Scan for stored or pending codes with an OBD-II tool.
3. Inspect the most common causes in this guide (visual checks first).
4. Run verification tests before replacing parts.
5. Repair, clear codes, and verify on a test drive.

## Symptoms and warning signs

When your 2016 Scion iM displays the "Key Fob Not Detected" message, you'll likely observe one or more of these specific symptoms:

- The engine does not crank or start when the push-button ignition is pressed.
- A prominent "Key Fob Not Detected" message appears on the dashboard display.
- The push-button start light may not illuminate green, or it might remain amber.
- The steering wheel may remain locked, preventing any movement.
- Remote lock/unlock functions on the key fob might still work, or they might also be intermittent/non-functional.
- Interior accessories (radio, lights) may or may not power on, depending on the specific cause.

## How to verify and confirm the issue

Before diving into complex repairs, there are several practical steps you can take to verify and confirm the root cause of the "Key Fob Not Detected" message on your 2016 Scion iM:

- **Replace the Key Fob Battery:** This is by far the most common culprit. A weak or dead CR2032 battery inside the fob can prevent proper communication. Try a fresh, high-quality battery.
- **Emergency Start Procedure:** Even with a dead fob battery, your Scion iM has an emergency start method. Hold the key fob directly against the push-button start switch and then press the start button. The vehicle uses an inductive coil to read the fob's transponder chip in close proximity.
- **Try a Spare Key Fob:** If you have a second key fob, test it. If the spare works, it strongly suggests an issue with the primary fob.
- **Check for Interference:** Remove other electronic devices (cell phones, smartwatches, other keys) from the immediate vicinity of the key fob and start button. Large metal objects or strong electromagnetic fields can sometimes interfere with the signal.
- **Inspect the Key Fob:** Look for any physical damage, signs of water intrusion, or corrosion on the battery terminals inside the fob.
- **Vehicle 12V Battery Check:** While less common for this specific message, a severely discharged or failing 12V car battery can cause various electrical system malfunctions, including issues with the smart key system. Check the battery voltage with a multimeter; it should be above 12.4V.

## Common causes (most likely first)

Understanding the potential causes can help narrow down your diagnosis for the 2016 Scion iM:

- **Dead or Weak Key Fob Battery:** As mentioned, this is the most frequent reason for the "Key Fob Not Detected" message.
- **Key Fob Malfunction:** The fob itself might be faulty due to internal damage, water exposure, or simply age, preventing it from transmitting a signal.
- **Interference:** Electronic devices, strong radio signals, or even certain types of tint on windows can sometimes block the fob's signal.
- **Vehicle 12V Battery Issues:** A low or failing car battery can lead to insufficient power for the Smart Key ECU to properly communicate with the fob.
- **Smart Key ECU/Receiver Malfunction:** The vehicle's onboard computer that receives the key fob's signal might be faulty. This is less common but can happen.
- **Wiring Issues:** Damaged or corroded wiring to the Smart Key ECU or the antenna that detects the fob can interrupt communication.
- **Push-Button Start Switch Failure:** The actual start button assembly could be faulty, failing to register the press or activate the system.
- **Immobilizer System Glitch:** The vehicle's anti-theft immobilizer system might experience a temporary glitch, preventing authorization. This can sometimes be reset by disconnecting the 12V battery for 10-15 minutes.

### Related guides on this vehicle

- [1997 Toyota Avalon Won't Start After Sitting for Days](/articles/car-wont-start-after-sitting-3900-toyota-avalon-1997)
- [2020 Toyota Corolla: Car Won't Start, No Fuel Pump Prime Sound](/articles/car-wont-start-no-fuel-pump-prime-toyota-corolla-2020)
- [Car Won't Start, No Click, No Crank 2017 Toyota Rav4 Diagnosis](/articles/car-wont-start-no-click-no-crank-toyota-rav4-2017)

## Step-by-step diagnosis and fixes

Follow these steps to diagnose and potentially fix the "Key Fob Not Detected" issue in your 2016 Scion iM:

1.  **Replace Key Fob Battery:** Purchase a new CR2032 battery. Open the key fob (usually with a small screwdriver or coin) and replace the old battery. Test immediately.
2.  **Perform Emergency Start:** If a new battery doesn't work, hold the key fob directly against the push-button start button. Press the brake pedal and then press the start button. If the car starts, it confirms the fob's transponder chip is working, but the remote signal is not.
3.  **Test with Spare Fob:** If you have a second key, try starting the car with it. If the second fob works, the problem is isolated to your primary fob.
4.  **Check Vehicle Battery:** Use a multimeter to check the voltage of your car's 12V battery. If it's below 12.4V, consider charging or replacing it. For more detailed information on battery health, you can browse our repair guides.
5.  **Inspect Fob for Damage:** Carefully examine the key fob for any signs of physical damage, water intrusion, or corrosion on the internal components. If damaged, a new fob may be necessary.
6.  **Reset Vehicle Electronics:** Disconnect the negative terminal of your 12V car battery for 10-15 minutes. Reconnect it and try starting the car. This can sometimes clear minor electronic glitches.
7.  **Check Fuses:** Consult your owner's manual for the location of fuses related to the Smart Key system or ignition. Visually inspect these fuses for any breaks.
8.  **Professional Scan Tool:** If the issue persists, a professional technician can use an advanced scan tool to check for specific diagnostic trouble codes (DTCs) related to the immobilizer or smart key system. Codes like B2799 (Engine Immobilizer System Malfunction) or B2780 (Key Not Detected) can pinpoint the problem.

## Repair options and cost factors

The cost and complexity of repairs for a "Key Fob Not Detected" message on your 2016 Scion iM vary significantly based on the root cause:

-   **Key Fob Battery Replacement:** This is a DIY fix, costing only a few dollars for a new CR2032 battery.
-   **New Key Fob:** If your existing fob is faulty, a replacement can be expensive. A new OEM key fob from Toyota/Scion, including programming, can range from $200-$400 or more. Aftermarket fobs are cheaper but may not always be reliable or easily programmable.
-   **Vehicle 12V Battery Replacement:** If your car battery is the culprit, replacement typically costs $150-$300, depending on the battery type and installation.
-   **Smart Key ECU/Receiver Replacement:** This is a dealer-level repair and can be quite costly, often running into several hundred dollars for the part alone, plus labor and programming.
-   **Wiring Repair:** If a specific wire is damaged, the cost will depend on the location and extent of the damage, usually involving diagnostic time and a few hours of labor.
-   **Diagnostic Time:** If you take your vehicle to a professional, expect to pay for diagnostic labor, which typically ranges from $100-$200 per hour.

## When to see a professional

While many "Key Fob Not Detected" issues can be resolved with simple DIY steps, there are situations where professional help is essential for your 2016 Scion iM:

-   If you've replaced the key fob battery and performed the emergency start procedure without success.
-   If both of your key fobs fail to work.
-   If you suspect a deeper electrical issue, such as a faulty Smart Key ECU or complex wiring problems.
-   If you're getting other unrelated warning lights or symptoms that suggest a broader system failure.
-   When diagnostic trouble codes (DTCs) are present that require specialized tools to interpret and address. For more information on your vehicle's systems, you can always [browse vehicles](/vehicles) and their common issues.

## Frequently asked questions

### Why does my 2016 Scion iM say "Key Fob Not Detected" even with the fob inside?

This message typically indicates a communication failure between your key fob and the car's smart key system. The most common reason is a dead or weak battery inside the key fob, preventing it from transmitting a strong enough signal to the vehicle's receiver.

### Can a low car battery cause the "Key Fob Not Detected" message on a Scion iM?

While less common than a dead fob battery, a severely discharged or failing 12V car battery can indeed cause various electrical system malfunctions, including issues with the smart key system. The car's electronics might not have enough power to properly detect or authorize the key fob.

### Is there an emergency start procedure for the 2016 Scion iM with a dead key fob battery?

Yes, your 2016 Scion iM has an emergency start procedure. Even with a dead key fob battery, you can usually start the car by holding the key fob directly against the push-button start switch while pressing the brake pedal, then pressing the start button. This allows the car to read the fob's transponder chip inductively.

## Sources and further reading

For detailed technical specifications and repair procedures, always refer to the official Toyota/Scion service manuals for your 2016 Scion iM.

This article is for informational purposes only and is not a substitute for OEM service procedures; always use a qualified technician for safety-critical work.

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