P20C4

Reductant Heater C Control Circuit High

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$28–167 (est.)

Symptoms

Check Engine light comes on
Reducing engine power (limp mode)
Increased fuel consumption
SCR system error message on dashboard
Problems starting in cold weather

Causes

Open or short circuit in the heater circuit
Heating element malfunction
Relay or fuse problems
SCR control module malfunction
Corroded contacts or damaged wiring harness

How to Fix

Check heater circuit fuses and relays
Inspect the wiring harness for damage
Check the resistance of the heating element
Scan the SCR control module for additional errors
If necessary, replace the heating element or wiring

Related codes

P20C3 P20C5 P20C6