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MID 128 PID 45 FMI 3Severity: Warning

MID 128 PID 45 FMI 3: Preheater Relay - Voltage Above Normal (Volvo)

Quick Answer

Preheater Relay - Voltage Above Normal (Volvo)

Code
MID 128 PID 45 FMI 3
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

  • Preheat relay solenoid shorted
  • Short circuit to high source in measuring line

Common Fixes

  • Inspect preheat relay wiring for shorts to battery
  • Check relay coil resistance
  • Test relay operation
  • Replace faulty relay
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What does MID 128 PID 45 FMI 3 mean?

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Preheater Relay - Voltage Above Normal (Volvo)

Detailed guide for MID 128 PID 45 FMI 3

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MID 128 PID 45 FMI 3 - Preheater Relay

**Fault Type:** Voltage above normal or shorted to high source

Fault Condition

  • Short Circuit + (Measuring line)

Possible Symptoms

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

Possible Causes

  • Preheat relay solenoid shorted
  • Faulty harness

Diagnostic Tips

1. Inspect preheat relay wiring for shorts to battery voltage

2. Test relay coil resistance (should be within spec)

3. Check for damaged connectors at relay and ECU

4. Verify proper operation of preheat relay with diagnostic tool

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