Question 1

My 2009 RDX key broke in the ignition. Can you get it out and make a new one on site?

Accepted Answer

Yes. The 2009 RDX uses a standard mechanical ignition cylinder with a laser-cut sidewinder blade, HU66 profile. If the flip blade snaps at the pivot, which is a known weak point on the N5F0602A1A housing, I can extract the broken piece without pulling the whole cylinder.

Once it is out, I decode the cut from the remaining lock data or the broken fragment, build a new blade, and program the immobilizer through the OBD-II port. If the original PCF7936 chip is still intact, sometimes I can transplant it. If not, I register a fresh ID46 transponder so the green key light clears and the car starts normally.

Question 2

What exactly is a remote flip key on this RDX, and how is it different from a regular key?

Accepted Answer

Three systems in one housing.

First, the laser-cut sidewinder blade that physically turns the ignition. Second, a Philips/NXP PCF7936 ID46 transponder chip that communicates with the Acura immobilizer ring antenna around the cylinder. Third, a 315 MHz remote transmitter, powered by a CR1616 coin cell, handling lock, unlock, hatch, and panic.

FCC ID is N5F0602A1A. Acura lists the assembly under part number 35111-STX-329, with driver memory variants under the broader 35111-STX family. The remote side can be registered with a pairing procedure, but the immobilizer chip side requires professional diagnostic access to the ECU. Two different systems, one shell.

Question 3

The green key light is flashing and the engine cranks but won't start. What is happening?

Accepted Answer

The immobilizer is not recognizing your transponder. Period.

On this RDX, when the ECU does not read a valid ID46 code from the key head, the engine cranks but fuel injection stays disabled. The dash shows a blinking green key icon. The owner's manual specifically notes this indicator and even mentions that metal near the ignition can interfere with the signal.

Common causes I run into in Oxnard:

- Aftermarket key cut with the wrong chip type or no chip at all
- Cracked PCF7936 inside the flip head from a drop
- Key shell swap where nobody transferred the original transponder
- New key that was never registered to the immobilizer ECU

It needs diagnosis, not repeated cranking.

Question 4

I bought a replacement flip key shell online. Can I just move my old chip over and skip programming?

Accepted Answer

This comes up a lot on Acura forums. In theory, yes, if you carefully extract the PCF7936 chip from the old housing and seat it correctly in the new shell, the immobilizer should still see it because the chip code has not changed. But "carefully" is doing heavy lifting there. The ID46 chip in these is small, fragile, and glued into a pocket in the key head. People crack them prying with a flatblade screwdriver. If the chip breaks, you are back to a no-start and now you need professional programming anyway. If you already have the shell and want it done right, bring it to me and I will handle the swap or cut a new blade and register a fresh chip on site.

Question 5

Can I program a spare key to my 2009 RDX myself without any special tools?

Accepted Answer

No. Not on this system. The 2009 RDX immobilizer does not support an owner add-key procedure like some older Hondas with the ignition on/off cycling trick. That method works on certain non-transponder or older-generation setups, but the ID46 crypto handshake on the first-gen RDX requires a registered seed/key exchange through the OBD-II diagnostic port. No shortcut, no ignition dance. The remote fob buttons can be paired with a hold-and-press sequence, but the transponder that actually lets the engine start needs pro-level equipment. Two different registrations, two different processes.

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