P21CC

Reductant Control Module Supply Voltage High

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
Increased fuel consumption
SCR system error message on dashboard
Increased NOx emissions

Causes

Problems with the generator (voltage in the on-board network is too high)
Reagent control module malfunction
Damage to the wiring harness to the module
Short circuit in power supply
Relay or fuse problems

How to Fix

Check the voltage in the on-board network (should be 13.5-14.5V with the engine running)
Inspect the wiring harness to the module for damage
Check fuses and relays in the module power circuit
Test the reagent control module
If necessary, replace the control module

Related codes

P20EE P21CB P21CD