5 Warning Signs
- Reduced airflow — the heater or AC blows weaker than usual, even on high.
- Musty smell — an unpleasant odour when you turn on the ventilation.
- Increased noise — the blower motor sounds louder as it works harder.
- Hay fever symptoms — increased sneezing or itchy eyes while driving.
- Foggy windscreen — the demister works poorly because airflow is restricted.
Recommended Intervals
Change every 12,000–15,000 miles or 12 months, whichever comes first. In high-pollen or urban areas, every 6 months is better. Some premium brands like BMW and Mercedes specify longer intervals (up to 20,000 miles) but shorter is always safer for air quality.
Frequently Asked Questions
Can a dirty cabin filter affect fuel economy?
Indirectly — if the filter is so clogged that the AC compressor works harder to maintain temperature, fuel consumption can increase slightly.
Is it worth changing the cabin filter before spring?
Absolutely. Fresh filters trap the most pollen when new. Changing in March gives you maximum protection for the worst of hay fever season (April-July).
Recommended Products
How we check fitment for this guide
We cross-reference fitment figures against manufacturer specifications and OE-supplier catalogue data where available, and matched to the standard codes that actually govern fit — battery type/group sizes, wiper lengths and fitting types, bulb fitment codes, tyre size markings, and oil specifications. We work by make, model, year, engine, and build date, because a single model can take different parts across its life. Where the right part depends on your exact vehicle, we tell you to confirm by registration or VIN. More on our method →