07/10/2026
π§ Mercedes A-Class β When the First Repair Doesnβt Fix the Fault
We recently had this Mercedes A-Class brought to WH Autos after another garage had been unable to get to the bottom of an engine management light.
The vehicle was originally diagnosed with a fault relating to the purge valve. The first garage replaced the purge valve and cleared the fault, but unfortunately, just a few days later, the engine management light returned.
Thatβs when the vehicle came to us for a proper diagnostic investigation. π
As an independent Mercedes-Benz specialist, we have access to Mercedes-Benz technical information and XENTRY diagnostic software, allowing us to investigate the fault using the correct manufacturer information.
During our diagnosis, we found a relevant Mercedes-Benz TIPS technical case which highlighted the fault code and the correct diagnostic procedure. This directed us to check the operation of the purge valve and investigate possible contamination within the system.
Our further testing identified that the charcoal canister had failed, which was the underlying cause of the problem.
We then:
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Supplied and fitted a genuine Mercedes-Benz charcoal canister
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Checked and cleaned the relevant lines
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Replaced the purge valve
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Used Mercedes-Benz XENTRY diagnostic software
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Cleared the fault codes
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Carried out a full service
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Replaced the engine oil and oil filter
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Replaced the engine air filter
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Replaced the dust/pollen filter
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Replaced the spark plugs
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Updated the Mercedes-Benz Digital Service History
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Carried out an MOT
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Carried out an extended road test
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Rechecked the vehicle to confirm the repair was successful
The vehicle was returned to the customer with the original fault fully rectified, fully serviced, MOTβd and the Digital Service History updated.
This is a great example of why proper diagnostics are about more than simply reading a fault code and replacing a part.
At WH Autos, we use manufacturer-level diagnostic equipment, technical information and proper testing procedures to find the root cause of the problem rather than simply replacing parts and hoping for the best.
π WH Autos β Independent Mercedes-Benz Specialist
Rear 426 Upper Elmers End Road, Beckenham, BR3 3HQ
π 07908 945215
π WHAutos.co.uk
Mercedes-Benz specialist knowledge. Dealer-level diagnostics. Independent prices.