P0618
Alternative Fuel Control Module KAM Error
Alternative fuel control module
Generic OBD-II
Medium
What it means
P0618 means the alternative-fuel control module — used on CNG, LPG, or similar systems — has a Keep-Alive Memory (KAM) error: it lost or corrupted the settings it stores between key cycles. On alternative-fuel vehicles this can make the fuel system run poorly or default to a backup mode, though the engine typically still starts.
Medium
Can I keep driving? The engine usually still runs — on bi-fuel vehicles it may drop back to gasoline or run rough on the alternative fuel; get it diagnosed.
Common symptoms
What you'll notice
- Check-engine light on
- Rough running or reduced power on the alternative fuel
- System defaulting to gasoline on bi-fuel vehicles
- Poor fuel economy
Common causes
Most likely first
- Weak, corroded, or loose battery terminals (Keep-Alive Memory loses its holding power)Likely
- Failed alternative-fuel control moduleCommon
- Open or short in the module's wiring or power feedCommon
- Faulty ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Check battery voltage and clean/tighten the battery terminals and grounds first.
- Inspect the module's power, ground, and harness for opens and shorts.
- Clear the memory error and see whether it returns.
- Reprogram or replace the alternative-fuel control module if it persists.
- Replace the ECM only as a last resort.
FAQ
Quick answers
Is it safe to drive with P0618?+
The engine typically still runs, often on gasoline, but have the alternative-fuel system checked so it operates correctly.
Can I just clear P0618?+
It may clear, but it returns if a weak power feed or a failing module keeps corrupting the module's memory.
Related codes
Often seen with P0618
Read & clear P0618 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX