Engine bay pressure washing causes misfire

Tags: #engine-bay · #spark-plug · #misfire · #dealer

An owner had the engine bay pressure-washed (керхер/Kärcher-style) at the dealership car wash when buying the car. Water intruded into the cylinder-1 spark plug well, causing ignition misfires (P0301-type fault) within the first 10,000 km — the owner also had already cut out the catalytic converter by that point¹. A photo documents water/fluid extracted from the spark plug well with a syringe². Advice from the affected owner: do not pressure-wash the engine bay ("подкапотка") the way dealerships sometimes do — gentle rinsing only, if cleaning under the hood at all³. The owner noted that without an OBD reader (ELM327-type adapter) on hand, they would have kept paying for diagnostics at a shop every time the fault recurred⁴.

Media

Water/fluid extracted from a spark plug well with a syringe, showing the water intrusion caused by pressure-washing the engine bay

Related pages

• Cylinder misfire — coil, plug, or valve
• Engine "loses sync" and stalls — diagnosis
• Catalytic converter failure — P0420/P0430 codes
• Engine bay cleaning with a pressure washer
• Off-road wiring damage and full-system fault diagnosis

Sources

This page is compiled from 4 community messages. Every fact carries a numbered reference to its original author and message.

Last updated: 2026-07-24