1. What is P0204?

The P0204 trouble code indicates a malfunction in the fuel injector circuit for cylinder “D”. When the ECM/PCM detects an electrical problem, the injector may not deliver proper fuel, causing misfires or poor engine performance.

2. Common Causes in Honda Civic & Jeep Grand Cherokee

• Faulty fuel injector “D”
• Damaged wiring harness or connector
• Blown fuse or ECM relay problem
• Corrosion or loose terminals
• ECM/PCM internal fault

3. Key Symptoms

• Check Engine Light (CEL) is ON
• Rough idle or engine misfire on cylinder “D”
• Poor fuel economy
• Difficulty starting or stalling
• Unusual exhaust smoke or odor

4. Models Prone to P0204

P0204 commonly appears in:

• Honda Civic 2006-2015
• Jeep Grand Cherokee 2011-2020
• Other models using multi-port fuel injection with cylinder D

5. Diagnostic Steps with ICARZONE UR1000

Use ICARZONE UR1000 to accurately read and clear P0204 codes. Steps:

1. Connect UR1000 to OBD-II port
2. Read fault codes and note freeze frame data
3. Test injector voltage with live data
4. Inspect wiring harness and connectors for damage
5. Perform injector activation test if supported
6. Clear code and retest after repair

6. Fixes & Execution

• Replace faulty fuel injector “D”
• Repair or replace damaged wiring/connectors
• Check and replace fuses or ECM relays if needed
• Clean corroded terminals
• Update or replace ECM if internal fault detected

7. Repair Costs & Safety Tips

• Fuel Injector Replacement: $120-$250 per injector
• Wiring Repair: $50-$150
• ECM Diagnostics: $80-$150
• Labor: $70-$120/hour depending on shop

Always disconnect the battery before working on fuel circuits. Use gloves and eye protection when handling fuel injectors.

8. Preventive Maintenance

• Use high-quality fuel and additives periodically
• Inspect fuel injector connectors and wiring annually
• Clean fuel injectors every 30,000-50,000 miles
• Regularly check fuses and ECM relays

9. FAQ

10. Summary

P0204 is a fuel injector “D” circuit malfunction that can cause misfires, rough idle, and poor fuel economy. Diagnose accurately with ICARZONE UR1000, inspect wiring and injectors, repair or replace faulty components, and maintain your fuel system to prevent recurrence.