The cold-start air pump system isn't performing correctly.
P0410 — also written PO41O, P 0410, 0410 — is the OBD-II code for secondary air injection system malfunction. Same code, same fix: this page covers every spelling of it.
This code means your 'hairdryer' pump isn't shoving extra oxygen into the exhaust to heat the cat up quickly. It's a classic headache on older Mercedes SLKs and Vauxhall Ecotec engines.
P0410 is a emissions fault code, typically costing £200–£800 to put right in a UK garage.
What P0410 actually feels like to drive
- A loud 'vacuum cleaner' or 'jet engine' noise from under the bonnet for the first 60 seconds after a cold start.
- A sudden drop in revs or a slight stumble just as the air pump shuts off.
- Engine management light (EML) glowing amber, often appearing a minute after driving off from cold.
- A strange 'mooing' or clicking sound when the engine is idling during warm-up.
- The car failing its MOT on the 'Major' defect of having an active EML, even if the emissions are actually okay.
What causes P0410?
- Failed air pump
- Blocked hoses (very common)
- Failed check valve
UK vehicles that throw P0410 most often
- Mercedes-Benz SLK 200/230 (R170/R171) 1998-2008
- Vauxhall Astra/Zafira 1.8 (Z18XE) 2000-2005
- Volkswagen Golf Mk4 2.0 (APK/AZJ) 1999-2004
- Subaru Impreza 2.5 WRX (EJ25) 2006-2008
- Mercedes-Benz C-Class (W203) C180/C200 Kompressor 2000-2007
- Saab 9-3 2.0t (B207) 2003-2006
How P0410 is fixed
- Replace air pump
- Clear or replace hoses
- Replace check valve
The P0410 misdiagnosis that wastes money
I’ve seen dozens of lads waste money throwing a new air pump at this before checking the basics. They assume because they can't hear the 'jet engine' whirring on a cold start, the motor is fried. In reality, a £40 check valve has usually failed first, allowing acidic exhaust moisture to backflow into the pump. You fit a new £300 pump without fixing the valve, and you’ll be doing the job again in three months when the new one drowns. Always check for water in the hoses first.
What a UK garage should charge for P0410
A basic diagnostic plug-in will cost you £50-£80 at an indy. If it’s just a split vacuum hose, you’re looking at £100 total. A Pierburg or Bosch air pump is pricey—expect to pay £250-£400 for the part alone, plus £120 labour. If you go to a Mercedes main dealer, they’ll easily quote you £800+ for the full 'kit' (pump, valve, and relay). We usually source the OEM parts from factors like Euro Car Parts or GSF to keep the bill under £500.
P0410 repair cost in the UK
Most P0410 repairs land between £200–£800 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0410
If your garage tells you the pump is dead, ask them to 'bench test' it with a 12v feed and show you the check valve. If that valve is full of carbon or moisture, the pump was a victim, not the cause. Also, on older Mercs, insist they check the relay in the SAM module—it’s a £15 part that sticks and burns the pump out. Don't let them just clear the code; it’ll come back the second the temperature drops outside and the ECU triggers a cold-start cycle.
Can you drive with P0410?
Yes but MOT emissions risk.
Urgency: low.