Lost Communication with Alternative Fuel Control Module
The powertrain control module (PCM/ECM) has detected a loss of serial communication with the Alternative Fuel Control Module (AFCM) over the CAN bus or other vehicle communication network. This code means the PCM is not receiving status messages or data from the AFCM within a calibrated time, preventing proper coordination of the alternative fuel system (CNG, LPG, Hydrogen, etc.).
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Open, short-to-ground, or short-to-voltage circuit on the CAN bus (High/Low) to the AFCM
- Damaged, corroded, or loose connectors at the AFCM or PCM
- Internal failure of the Alternative Fuel Control Module (AFCM)
- Loss of battery voltage (B+) or ground at the AFCM
- Internal PCM/ECM failure (rare)
- Software error or incompatible programming in one of the modules
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Alternative fuel system inoperative or not switching fuels
4. Step-by-Step Diagnosis
Scan for other related communication codes (U-codes) and check for any stored freeze frame data.
Inspect the AFCM connector and wiring for damage, corrosion, or loose terminals.
Check for battery voltage and ground at the AFCM connector.
Test the CAN bus wiring (High and Low) for continuity, shorts, and proper termination resistance (60 ohms typical).
If wiring and power are good, attempt to communicate with the AFCM using a scan tool; if no response, suspect a failed AFCM.
As a last resort, check for PCM software updates or replace the PCM if all else fails.
5. Frequently Asked Questions
Is it safe to drive?▼
The vehicle may still run on gasoline, but the alternative fuel system will be disabled. Driving with this code is possible but not recommended for extended periods, as it may affect emissions and fuel system coordination. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs vary widely: from $100–$200 for a simple wiring repair or connector cleaning, to $500–$1,200 for AFCM replacement, and potentially $800–$2,000+ if the PCM needs replacement.