B2799Anti-Theft

Engine Immobilizer System Malfunction

B2799 indicates a fault in the engine immobilizer (anti-theft) system. The immobilizer cannot verify the key or communicate with the engine control module, so it may block starting.

🚗 Often not, since the immobilizer may prevent the engine from starting.

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

#1Faulty key transponder or worn key$50-$300

35%

A damaged transponder key is not recognized by the immobilizer.

#2Immobilizer antenna ring fault$100-$350

30%

The antenna ring around the ignition fails to read the key.

#3Module communication or wiring fault$100-$500

25%

Loss of communication between the immobilizer and the ECM.

🩺 Common Symptoms

Engine cranks but will not start
Security or key light on
Immobilizer message on display
Intermittent start failures

💰 Repair Cost: DIY vs Shop

DIY Cost

$50-$300

Shop Cost

$150-$600

📋 Free OBD2 Code Cheat Sheet

The 50 most common codes with likely cause and DIY fix cost. Sent once, no spam.

🔧 How to Diagnose B2799

1Try a known-good spare key

2Inspect the ignition antenna ring and its connector

3Scan for immobilizer communication codes

4Reprogram keys or repair the antenna as indicated

❓ Frequently Asked Questions

Why won't my car start with B2799?

The immobilizer cannot verify your key, so it blocks the engine from starting.

Will a spare key fix B2799?

Sometimes, if the original transponder key is worn or damaged, a good spare will start it.

What causes B2799?

A bad transponder key, a failed antenna ring, or a communication fault with the engine module.

🔗 Related Codes

B2960B2205P0513U0155