These instructions apply to the Ford Focus Mk2 (DA3) 2004-2012.
For other models, please choose your vehicle here.
The Ford Focus (Mk2, 2004–2012) uses a Passive Anti-Theft System (PATS), and few owners know it can tell you what is wrong through its warning light. When the immobiliser detects a fault it flashes a two-digit code at the anti-theft / security light in the instrument cluster. This guide shows how to read that code and lists what each one (11–23) means — a quick, free way to tell an immobiliser or key fault from an ordinary flat-battery non-start.
Normal Flashing vs a Fault Code
It helps to know what is normal first. About 5 seconds after you switch the ignition off, PATS arms itself and the anti-theft light flashes once every 2 seconds — that steady slow blink means the immobiliser is simply armed, not faulty. If instead the system finds a problem, the light flashes rapidly (about 4 Hz) for one minute, or lights steadily for a minute, and then begins flashing a two-digit error code.
How to Read the Flash Code
- Watch the anti-theft / security symbol in the instrument cluster after the rapid one-minute warning.
- Count the first burst of flashes — that is the first digit.
- After a one-second pause, count the second burst — that is the second digit.
- After the second digit there is a longer three-second pause, then the whole code repeats. Watch it through twice to be sure.
For example, one flash, a pause, then three flashes is code 13 — no valid key was detected.
Flash Code Table
| Flash code | Meaning | Where it points |
|---|---|---|
| 11 | Transceiver not connected or has no power | The reader coil (transceiver) around the ignition barrel — connection or supply |
| 12 | Transceiver fault | The reader coil itself |
| 13 | No key / no PATS key used to turn the ignition | Wrong or non-chipped key, or the transponder not being read |
| 14 | Incomplete key code received | Weak or partial transponder read |
| 15 | Invalid key code received | Key not matched to this car |
| 16 | CAN communications error | Network fault between modules |
| 21 | Not enough keys programmed (minimum of 2) | Key programming / configuration |
| 22 | Non-volatile memory configuration error (initialisation or end-of-line configuration missing) | Module configuration |
| 23 | Codes from the instrument cluster and powertrain control module (PCM) do not agree | Cluster / PCM mismatch after a module change |
What the Two Groups Mean
Codes 11–16 are about reading the key: the transceiver coil, the transponder chip in the key, or the network carrying that data. Start with the obvious — the correct chipped key, a fob held properly in the barrel, and no second transponder (or a metal keyring) crowding the reader. Codes 21–23 are about programming and module configuration; the car needs at least two programmed keys, and a cluster or PCM that has been swapped must be configured to match. Those are dealer tasks — on this generation additional keys and configuration are done with Ford diagnostic equipment (WDS), not a home sequence.
Frequently Asked Questions
My anti-theft light just blinks slowly all the time — is that a fault? No. A single flash every two seconds after the ignition is off is the normal “armed” signal. A fault shows as a fast one-minute warning followed by a repeating two-digit code.
The car won’t start and the light flashes a code — what now? Read the two-digit code from the table above. An 11–16 usually points to the key or its reading; try your other programmed key first. A 21–23 is a programming or module issue for a dealer.
Does a flat key-fob battery cause these codes? No. The Focus Mk2 is a twist-key car and the transponder is powered by the reader coil, so a flat coin cell does not stop starting or trigger a PATS code — that is a separate remote-battery issue.
Can I add a key or clear these myself? The car comes with two keys and holds up to eight, but extra keys and configuration are coded with Ford diagnostic equipment at a dealer or auto-locksmith. There is no owner sequence for the transponder side.
If a stored engine or body fault code is involved rather than the immobiliser, look it up on our sister site autodtcs.com.
Independent guide — not affiliated with Ford. Always follow your official service manual and safety precautions. Read our full disclaimer.