Engine
Camshaft
The camshaft controls when the intake and exhaust valves open and close.
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Combustion flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Lobe shapes open valves at the right time
- Drives the fuel pump on many engines
- Operates lifters, rockers or buckets
When it fails
- Ticking or tapping noise at the top of the engine
- Poor performance
- Camshaft codes (P0340 family)
- Rough idle
How to diagnose
- Listen with a stethoscope at the valve cover
- Check oil level and condition
- Inspect timing marks
Maintenance
- Change oil on schedule (cam lobes fail on dirty oil)
- Adjust valve clearance when due
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.
Related part
Timing Belt / Chain
The timing belt or chain keeps the crankshaft and camshaft synchronized for correct valve timing.