Land Rover OBD-II Trouble Codes
-------------------------------------------------The diagnostic trouble code (DTC) P1622 indicates a "Repeated Wrong ECM Security Code Fault," and the DTC P1623 specifically points to an "ECM Security Code Fault." These codes suggest issues related to the security features of the Engine Control Module (ECM) or Powertrain Control Module (PCM).
Immobilizer Authentication Error,
Anti-Theft Code Mismatch,
ECM-Smartra Communication,
Security Key Invalid,
Smart Entrance Control Fault,
Diagnostic Overview
The System: This code is part of the vehicle's anti-theft (Immobilizer) system. The Engine Control Module (ECM) and the Immobilizer module (often called a SMARTRA or Security Control Unit) must perform a "handshake" using a specific security code or "PIN" before the engine is allowed to start.
P1623: This fault indicates that the security code sent by the key or the immobilizer module does not match the code stored in the ECM. As a result, the ECM will disable fuel injection or ignition, and the car will likely crank but not start.
Common Failure Points
Unprogrammed or Generic Key: If you recently had a new key cut that wasn't properly "paired" to the vehicle’s computer using a professional scan tool, this code will trigger.
Antenna Coil Failure: There is a ring of wire around the ignition cylinder (the Transponder Antenna) that reads the chip in your key. If this ring is cracked or disconnected, the security code won't reach the ECM.
ECM/PCM Replacement: If the Engine Control Module was replaced with a used unit from another car, it still has the "old" car's security code and will reject your current keys.
Wiring Interference: Aftermarket remote starters or low-quality LED lights installed near the steering column can sometimes interfere with the sensitive radio frequency (RF) signal of the key chip.
Symptoms
Crank, No Start: The engine turns over but never fires up.
Security Light: The "Key" or "Lock" icon on the dashboard may stay solid or flash rapidly.
Intermittent Start: The car might start fine one day and refuse the next if the antenna coil is starting to fail.
Troubleshooting Steps
Try the Spare Key: If the car starts with your spare key but not your primary key, the chip inside the primary key is damaged or has lost its programming.
Battery Reset: Disconnect the battery for 10 minutes. Sometimes the "handshake" logic between modules can freeze, and a hard reset forces them to re-communicate.
Check the Antenna Ring: Remove the plastic steering column cover and ensure the wiring to the ring around the key hole is tight and free of corrosion.
Professional Re-programming: Most P1623 codes require a high-end scan tool or a locksmith to "re-learn" the security codes between the ECM and the keys.
Would you like me to check if there is a manual "Emergency Key" procedure for your specific vehicle to get it started temporarily?
How an Immobilizer System Works and Fails
This video explains the communication process between the transponder key and the ECM and how to identify if the fault is in the key chip or the antenna coil.
Here are some potential causes and diagnostic steps for these codes:
### Possible Causes:
1. **Incorrect Security Code Entry:** Repeatedly entering the wrong security code during attempts to access or communicate with the ECM.
2. **Faulty ECM Security System:** Malfunction in the ECM's security system that prevents successful code entry or authentication.
3. **Faulty Key or Immobilizer System:** Issues with the key, key fob, or the vehicle's immobilizer system that affect the security code validation.
4. **Wiring or Connector Issues:** Problems with the wiring or connectors associated with the ECM or security-related components.
5. **Faulty ECM:** A malfunction within the ECM itself that hinders proper security code validation.
### Diagnostic Steps:
1. **Verify Security Code Entry:** Ensure that the correct security code is being entered during attempts to access or communicate with the ECM.
2. **Check Key and Immobilizer System:** Verify that the key or key fob is functioning correctly and that the immobilizer system is properly recognizing and validating the key.
3. **Inspect Wiring and Connectors:** Inspect the wiring and connectors associated with the ECM and security-related components. Look for any signs of damage, corrosion, or loose connections.
4. **Attempt Code Entry with Alternative Method:** If applicable, try using an alternative method or procedure for entering the security code to rule out issues with the entry process.
5. **Check ECM Security System:** Diagnose the ECM's security system to identify any faults or malfunctions. This may involve using specialized diagnostic equipment.
6. **Perform System Diagnostics:** Use a scan tool or diagnostic equipment to perform comprehensive system diagnostics. Check for additional trouble codes and address any related issues.
7. **Verify ECM Functionality:** Ensure that the ECM is functioning correctly by testing its various functions and responses.
8. **Consider Professional Assistance:** If the issue persists or if you are unsure about diagnosing and addressing security-related faults, seeking assistance from a qualified mechanic or technician with experience in vehicle security systems is advisable.
Addressing security code faults is essential to ensure the proper operation and security of the vehicle. If in doubt or if the issue persists, seeking professional assistance is recommended for a thorough diagnosis and effective resolution.
