P0666
P0666: Engine Control Module (ECM) Output Circuit Malfunction
📖 What Does P0666 Mean?
Symptoms
- • Engine performance issues
- • rough idling
- • decreased power
- • and possible misfires
Common Causes
- • Faulty ECM output circuit
- • damaged or corroded wiring
- • or a malfunctioning ECM
Possible Solutions
1. Check the ECM output circuit for damage or corrosion and repair or replace as needed. 2. Inspect and clean the wiring harness. 3. Update the ECM software if necessary. 4. Replace the ECM if it is malfunctioning.
Fixing this on your car?
Get a vehicle-specific repair guide with exact parts, oil specs, and torque settings for your make and model.
🚙 Get Vehicle-Specific Fix Guide
Select your vehicle to see a customized repair guide with exact parts and specifications:
❓ Common Questions About P0666
Can I drive with code P0666?
You can drive for a short time, but should address code P0666 soon to avoid worsening the problem or failing an emissions test.
How much does it cost to fix P0666?
The estimated repair cost for code P0666 is between $100 and $500. This includes parts and labor for most makes and models.
Is this code easy to fix myself?
This repair is considered moderate. It may require specialized tools or significant disassembly. Professional help is recommended if you aren't an experienced DIYer.
Required Parts
Recommended Tools
Need a Pro?
Complex codes like P0666 can be tricky. Don't risk it if you're unsure.
Recommended Tool
Professional OBD2 Scanner
Read & clear codes, view live data, and reset service lights yourself.
View Best Sellers ↗Related Diagnostic Codes
Other codes that may appear with P0666
P0664: Engine Control Module (ECM) Output Circuit Malfunction
P0665: Engine Control Module (ECM) Output Circuit Malfunction
P0667: Engine Control Module (ECM) Output Circuit Malfunction
P0668: Engine Control Module (ECM) Output Circuit Malfunction
💡 Why These Codes Are Related:
- • Similar Issues: Same root cause or component failure
- • Related Problems: Often occur together due to system interactions
- • Sequential Codes: Progressive failure stages or multiple sensors
- • Same System: Components within the same automotive system