LOW RISK
Common symptoms
- See page for quick checks
Cost expectations
Typical costs vary by car and region. Use this as a ballpark.
- DIY / parts: £20–£80
- Garage / labour: £80–£250
Most likely causes (ranked)
Start at the top. Rule out the common, cheap causes before expensive ones.
- Blocked scuttle drains
- Door seal leak
- Heater matrix leak (coolant smell)
- Sunroof drains blocked
- Boot seal leak
Quick checks (fast, low-cost)
Fast checks you can do with basic tools before buying parts.
- Check for coolant smell (sweet) vs rain water.
- Inspect scuttle drains and clear debris.
- Run hose test around doors/windows.
- Check heater matrix for misting windows and coolant loss.
- Dry thoroughly to prevent mould.
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
- If coolant leak suspected, avoid driving long; fix heater matrix.
- Dry and treat to prevent corrosion and electrical faults.