OBD Guide

P20C4

Reductant Heater C Control Circuit High

P20C4 is an OBD-II diagnostic trouble code meaning: Reductant Heater C Control Circuit High. Common causes: open or short circuit in the heater circuit, heating element malfunction. Estimated repair cost: $28–167.

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

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

Related codes

Error P20C4 by Vehicle Brand

FAQ

What does the P20C4 code mean?

P20C4 is an OBD-II diagnostic trouble code that indicates: Reductant Heater C Control Circuit High

What causes a P20C4 error code?

The most common causes of P20C4 include: Open or short circuit in the heater circuit; Heating element malfunction; Relay or fuse problems; SCR control module malfunction.

How do I fix a P20C4 diagnostic trouble code?

To fix P20C4: Check heater circuit fuses and relays. Inspect the wiring harness for damage. Check the resistance of the heating element. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P20C4?

Limited driving only, diagnose soon

How much does it cost to fix P20C4?

The estimated repair cost for P20C4 is $28–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat