U0409

Invalid Data Received From Alternative Fuel Control Module

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$56–278 (est.)

Symptoms

Check Engine light comes on
Reduced engine power
The car switches to the main type of fuel
Increased fuel consumption
Unstable engine operation

Causes

Alternate fuel module malfunction
Open or short circuit in the communication circuit
Connector problems or contact corrosion
Software error in ECU
Module power problems

How to Fix

Check the integrity of the wiring harness to the module
Inspect and clean connector contacts
Check the power supply and ground of the module
Scan the module for additional error codes
If necessary, replace the alternative fuel module

Related codes

U0401 U0402 U0415