Cylinder 4 Pressure Too Low

Check these first

• A leaking compression ring on cylinder 4
• A burnt or poorly sealing exhaust valve on cylinder 4
• A failed cylinder 4 pressure sensor reading low
• An intake or exhaust leak at cylinder 4
• Tight valve lash on cylinder 4

What to do next

1. Run a compression test on cylinder 4 and compare to the rest
2. Run a cylinder leakdown test on cylinder 4
3. Compare the cylinder 4 pressure sensor to a known good one
4. Check valve lash on cylinder 4
5. Repair the valve or ring fault if the mechanical test confirms it
6. Clear the code and retest

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