U0666

Lost Communication With Reductant Pressure Sensor

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$56–167 (est.)

Symptoms

Check Engine Light Is On
Reduced engine power
SCR system malfunction message appears
Increased reagent consumption
Increased NOx emissions

Causes

Open or short circuit in the sensor circuit
Reagent pressure sensor malfunction
Connector problems or contact corrosion
SCR ECU malfunction
Problems with power or grounding of the sensor

How to Fix

Check the integrity of the sensor wiring and connectors
Check the power supply and grounding of the sensor
Test the reagent pressure sensor
Check the SCR ECU for errors
Replace reagent pressure sensor if necessary

Related codes

U0664 U0665 U0667