1. What Are Codes DF017–0190?

DF017: Glow-plug (preheat) module control circuit fault. DF018: Low-speed cooling fan circuit control issue. DF019: High-speed cooling fan circuit control fault. All are Renault manufacturer-specific DTCs found in older Diag-BOX/Can Clip diagnostics.:contentReference[oaicite:0]{index=0}

Why They Matter

These control systems are critical for cold starts (DF017) and thermal management (DF018/19). Faults can lead to no starts, overheating, and increased emissions.

Common issues include failed control modules, wiring shorts/opens, relay faults, or ECU mis-communication.

2. Common Causes & Examples

• Bad Preheat Module (DF017): Open or shorted relay inside, glow-plug doesn’t activate.
• Wiring Damage: Rodent-chewed harness or connector corrosion causing intermittent faults.
• Blown Relay or Fuse: Prevents power to glow plugs or fan motors.
• ECU Signal Error: Poor communication along CAN bus or broken control signal.

3. Symptoms

• Engine hard or fails to start when cold (DF017)
• Engine overheating at idle or slowed airflow (DF018/19)
• Warning lights or fuel trimming issues

4. Vehicles Affected

Found primarily on older Renault diesel models using Can Clip, such as:

• Renault Megane II / Scenic II
• Renault Kangoo 1.5 dCi
• Renault Laguna II

5. Diagnostic Flow

1. Read DF codes using UR1000 or Clip tool
2. Inspect fuses, relays, connectors of preheat/fan circuits
3. Check voltage and ground at module
4. Test module output to glow plugs or fan
5. Substitute known-good module if needed

6. Solutions & Execution

• Replace defective preheat/fan control module
• Repair corroded or damaged wiring
• Replace blown fuse or relay
• Update ECU software if communication errors persist

7. Repair Costs & Precautions

• Control module replacement: $120–300
• Wiring fix: $50–150
• Relay/fuse: $10–40

8. Preventive Measures

• Check wiring during routine service
• Use dielectric grease on connectors to prevent corrosion
• Run diagnostics pre-winter using UR1000

9. FAQ

10. Summary

Codes DF017–0190 point to faults in the glow plug or cooling fan control circuits in Renault diesels. Systematic diagnosis—scan, inspect power/ground, test modules—ensures accurate repairs. The iCarzone UR1000 tool speeds up live testing and fault isolation in minutes.