P1259 Code: Immobilizer to PCM Signal Error
⚠️ Severe · not recommended to drive
The engine may crank but not start, or stall right after starting, because the security system won't let it run.
What P1259 means
The engine immobilizer (anti-theft system) and the powertrain control module (PCM) can't communicate properly. The immobilizer is designed to block the engine from running unless it gets the right signal from the key, so this communication error can stop the engine from starting at all.
Symptoms
- Check engine light or theft light is on
- Engine cranks but will not start
- Engine starts then stalls
- No response from the key
- Security light flashing
Common causes
- most common: Faulty key or key transponder chip
- common: Faulty immobilizer module
- common: Damaged wiring between the immobilizer and PCM
- less common: Faulty powertrain control module
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Try a second programmed key to rule out a bad key | Yes | $0–50 |
| Replace or reprogram the key | Mechanic | $50–200 |
| Repair wiring between the immobilizer and PCM | Yes | $50–150 |
| Replace the PCM and have it programmed | Mechanic | $500–1200 |
Frequently asked questions
Can I drive with a P1259 code?
Probably not. The immobilizer may block the engine from starting or running, so the car is often undrivable until the fault is fixed.
Why won't my car start with P1259?
The anti-theft system can't confirm it's the right key, so it refuses to let the engine run. A faulty key chip is the most common cause.
How much does it cost to fix P1259?
A new or reprogrammed key is $50–$200. Replacing the PCM can run $500–$1,200 including programming.
Related codes
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.