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P0398 Powertrain

Cylinder 1 Pressure Sensor Circuit High

Cylinder 1 pressure sensor above upper plausibility — open signal or short to B+. 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

  • Cylinder pressure sensor

Common causes

  • High likelihood: Open signal line
  • Low likelihood: Connector pins corroded - high contact resistance
  • Low likelihood: Supply wire pinched against B+ source

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions

Related codes

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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