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P26D4 Powertrain

Engine Coolant Pump Supply Voltage Circuit Low

The dedicated supply voltage to the coolant pump module is below operating range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

Affected components

  • Smart coolant pump module
  • Supply circuit
  • Battery

Common causes

  • High likelihood: High-resistance battery feed
  • Medium likelihood: Weak battery sags under pump current
  • Low likelihood: Connector pins corroded - high contact resistance

Diagnostic notes

  • The malfunction indicator lamp may illuminate

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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