Experiencing issues starting your 2003 BMW 745Li and suspecting the key fob? It’s a common concern, especially if your key fob is acting erratically. While a seemingly simple issue like a dead key fob battery might be the culprit, it’s wise to investigate all possibilities. Let’s explore how to address potential starting problems in your 2003 BMW 745Li, starting with the key fob battery.
One frequent question among 745Li owners is whether a low key fob battery can prevent the car from starting. The answer is not always straightforward, but it’s definitely a good place to begin troubleshooting. A weak or dead battery in your 2003 BMW 745Li key fob can indeed lead to starting difficulties and other related problems.
Symptoms of a Failing Key Fob Battery
Before you delve into more complex diagnostics, consider if you’re noticing any of these symptoms associated with a low key fob battery:
- Intermittent Key Fob Functionality: Do you find yourself needing to press the buttons on your key fob multiple times to lock or unlock the doors? This can be an early sign of a weakening battery.
- Reduced Range: Have you noticed that you need to be closer to your 745Li for the key fob to work? A decreased operating range is another indicator.
- “Key Not Recognized” Errors: In some cases, a low battery might cause the car’s system to intermittently fail to recognize the key, potentially leading to starting issues.
- No Response from Comfort Access (if equipped): If your 2003 BMW 745Li has comfort access, a failing key fob battery can disrupt this feature, making it harder to unlock and start the car without directly using the key.
Step-by-Step 2003 Bmw 745li Key Fob Battery Replacement
Replacing the battery in your 2003 BMW 745Li key fob is usually a straightforward process you can do yourself. Here’s a general guide:
- Identify the Battery Type: You’ll need to determine the correct battery type for your specific key fob. Common types are CR2032 or CR2025. Consult your owner’s manual or examine the old battery once you open the fob to confirm.
- Open the Key Fob: Locate the small notch or release button on your key fob casing. Using a small flathead screwdriver or your fingernail, carefully pry open the casing. Some key fobs may have screws that need to be removed first.
- Remove the Old Battery: Once open, you’ll see the battery. Note its orientation (+ and – sides). Gently remove the old battery.
- Install the New Battery: Insert the new battery, ensuring it’s placed in the correct orientation.
- Close the Key Fob: Carefully snap the key fob casing back together until it’s securely closed. If screws were removed, re-install them.
- Test the Key Fob: Test the key fob functions (lock, unlock, trunk release) to ensure the new battery is working.
If Battery Replacement Doesn’t Solve the Starting Issue
If replacing the key fob battery doesn’t resolve the starting problem, particularly if your 2003 BMW 745Li is pushing the key out and exhibiting other electrical issues (like no iDrive, windows, or radio), then the problem is likely more complex than just a key fob battery.
Based on the original description of the 2003 BMW 745Li’s issues – “WONT START!, PUSHES KEY OUT!” and other electrical malfunctions after battery disconnection – simply replacing the key fob battery might not be the complete solution. These symptoms suggest potential problems beyond just the key fob, possibly related to:
- Car Battery Issues: Even if you charged the battery, it might be failing under load or have internal damage.
- Immobilizer System: The immobilizer system in your BMW might not be recognizing the key for other reasons.
- Key Fob Programming/Synchronization: While changing the battery shouldn’t unprogram the key, issues can sometimes arise. Resynchronizing the key to the car might be needed.
- General Electrical System Problems: The widespread electrical issues (no iDrive, windows, etc.) point towards a broader electrical system malfunction that requires professional diagnosis.
Next Steps for Diagnosing Starting Problems
If a new key fob battery doesn’t get your 2003 BMW 745Li running, consider these steps:
- Check the Car Battery: Have the car battery professionally tested to rule out a weak or faulty battery.
- Inspect Battery Connections: Ensure the battery terminals are clean and tightly connected.
- Consult a BMW Technician: Given the combination of “key pushed out” and broader electrical issues, it’s highly recommended to seek professional diagnosis from a qualified BMW technician or mechanic experienced with BMW 7 Series models. They can use specialized diagnostic tools to pinpoint the root cause of the problem, which could range from immobilizer issues to more complex electrical system faults.
While ensuring your 2003 BMW 745Li key fob has a fresh battery is a good first step, for more persistent starting problems, especially those accompanied by the key being rejected and other electrical failures, professional diagnostics are crucial to get your “baby back on the road.”
