OBD Codes List

Diagnostic reference · P03A5

P03A5

Cylinder 2 Pressure Too High

System
Ignition and misfire (P code)
Lamp
Check Engine Light
Category
Powertrain - Ignition

What it means

P03A5 means Cylinder 2 Pressure Too High.

Check these first

  • A pre-ignition or detonation event on cylinder 2
  • Heavy carbon buildup raising compression on cylinder 2
  • A failed cylinder 2 pressure sensor reading high
  • A mismatched piston or head on cylinder 2
  • Over-advanced timing on cylinder 2

What to do next

  1. Check live cylinder 2 pressure against the other cylinders
  2. Listen for detonation or ping on cylinder 2
  3. Compare the cylinder 2 sensor to a known good one
  4. Check base ignition timing and knock sensor data
  5. Repair carbon or timing faults if the mechanical test confirms it
  6. Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.