Blue smoke
Blue smoke usually means oil burning. Pinpoint whether it’s PCV, turbo seals, or engine wear.
HIGH RISK
Common symptoms
- Blue smoke on startup
- Blue smoke on overrun
- Blue smoke under boost
- Oil smell from exhaust
Cost expectations
DIY: £0–£120. Garage: £150–£1200+.
Note: prices vary by car and region. Use this as a planning range.
Most likely causes (ranked)
- PCV failure — High crankcase pressure pushes oil into intake.
- Turbo oil seals — Smoke under boost/after idling then rev.
- Valve stem seals — Puff of smoke after idle/overnight.
- Piston rings — Continuous smoke and high consumption.
- Overfilled oil — Can cause oil ingestion via PCV.
Quick checks (fast, low-cost)
- Check oil level (not overfilled).
- Inspect PCV and breather hoses.
- Check intercooler/turbo outlet for oil pooling.
- Watch when smoke occurs: start, overrun, boost.
- Compression test if continuous smoke and poor power.
Recommended tools
These tools make diagnosis faster and stop you buying random parts.
Related fixes
If your symptoms don’t match perfectly, check these next.
What to do next
- Avoid hard driving until confirmed.
- PCV issues can be cheap; ring wear is expensive.
- If smoke suddenly worsens, stop and inspect.
AutoSolveHub helps you narrow possibilities. Always confirm critical repairs with proper testing and safe procedures.