Question 1

How do I spot a fake or unqualified locksmith before I get burned?

Accepted Answer

A few things to watch for. If they quote a very low flat rate on the phone and then say they'll work out the final price on site, that's a bait-and-switch setup. It's common and it's been reported repeatedly by Mitsubishi owners who end up with a bill several times what was quoted.

Search the business name before anyone shows up. No real address, no reviews, a stock photo, and a generic listing are all bad signs. A legitimate locksmith who works on older Mitsubishis should be able to tell you, before they arrive, that your car uses a transponder key system, that it requires programming equipment, and that they've worked on this generation before. If they can't answer basic questions about the car's key system, they probably can't program it either.

Question 2

What exactly is a transponder key and why can't I just get one copied at a hardware store?

Accepted Answer

Your 2003 Eclipse uses a transponder key. There's a small chip embedded in the plastic head of the key. When you insert it and turn the ignition, the car's immobilizer reads a signal from that chip. If the chip isn't there, or isn't recognized, the engine either won't start or it starts and immediately stalls out.

A hardware store can copy the metal key blade, and that copy will turn the ignition just fine. But without a programmed chip, the immobilizer shuts the engine down. Programming requires a tool that communicates with the vehicle's security system and registers the new chip as an authorized key. That's not something a key kiosk can do.

Question 3

What tools do you actually use to program a key for a 2003 Eclipse?

Accepted Answer

For a standard add-a-key on a 2003 Eclipse where there's already a working key present, a professional-grade OBD-based programmer handles it. But when the job is all-keys-lost, or when a previous programming attempt left the immobilizer in a fault state, I go to the bench. That means pulling the module, reading and clearing the data directly, and rebuilding the key registration before anything else.

The reason I carry bench tools is exactly what happened with the car at The Crosby: another locksmith tried OBD-only, hit an error, and walked away. A bench approach bypasses the lock-out condition entirely. Mitsubishi owners have posted about this situation on forums more than once, usually after a locksmith or even a dealer said the module was bad. Often it isn't bad. It's just in a state that OBD tools can't clear on their own.

Question 4

My 2003 Eclipse starts and then immediately stalls. Could this be the transponder key?

Accepted Answer

Yes, that's a known symptom of an immobilizer that didn't recognize the key. Starts and immediately stalls, sometimes within one or two seconds, is the classic tell. The engine fires on the mechanical signal from the ignition, but the immobilizer cuts fuel or spark almost instantly when it doesn't see a valid chip signal.

It can also happen with a worn or damaged key where the chip inside has cracked, or with a key that was copied in blade only without a programmed chip. If you have a second key that starts the car normally, that confirms the problem is in the chip of the key you were using, not the car itself. If neither key works that way, the immobilizer or its antenna ring around the ignition cylinder is worth checking before assuming the module is at fault.

Question 5

Can I program a second transponder key for a 2003 Eclipse myself at home?

Accepted Answer

On some older vehicles there's an onboard add-a-key sequence you can do with the ignition. The 2003 Eclipse isn't one of the cars where that's a well-documented, owner-friendly process. Programming the transponder chip on these requires equipment that talks to the immobilizer system. Buying a pre-cut key blank online doesn't get you very far without the programming step. You'd still need someone with the right tools to complete the job.

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