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MID 128 PID 45 FMI 5Severity: Warning

MID 128 PID 45 FMI 5: Preheater Relay - Open Circuit (Volvo)

Quick Answer

Preheater Relay - Open Circuit (Volvo)

Code
MID 128 PID 45 FMI 5
Severity
Warning
Applies to
Check OEM application
Can I drive?
Driving suitability is not established by this code alone.

Common Symptoms

  • Preheat relay not activated
  • White smoke during cold start
  • Start problems in cold climate

Likely Causes

  • Open circuit in preheat relay circuit
  • Faulty preheat relay
  • Faulty harness

Common Fixes

  • Check relay continuity with multimeter
  • Inspect harness for broken wires
  • Check connector pins for damage
  • Replace faulty relay
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What does MID 128 PID 45 FMI 5 mean?

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Preheater Relay - Open Circuit (Volvo)

Detailed guide for MID 128 PID 45 FMI 5

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MID 128 PID 45 FMI 5 - Preheater Relay

**Fault Type:** Current below normal or open circuit

Fault Condition

  • Open Circuit

Possible Symptoms

  • Preheat relay not activated
  • White smoke during cold start
  • Start problems in cold climate

Possible Causes

  • Faulty Preheat relay
  • Faulty harness
  • Open circuit in wiring

Diagnostic Tips

1. Check relay coil continuity with multimeter

2. Inspect harness for broken wires or poor connections

3. Verify power and ground at relay socket

4. Check for corrosion or damage at connector pins

5. Test relay by applying power directly

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