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richardhunter1

Citan diesel boost issue diagnosis

My 2013 Mercedes Citan diesel is experiencing boost issues with 135538 km The check engine light is on power is significantly reduced and the engine response is sluggish It occasionally stalls at idle and fuel consumption has increased I'm also hearing a whistling noise turning into a loud hiss when accelerating I suspect a wastegate valve problem I've checked the MAP sensor and throttle body visually but haven't found any obvious issues Could a faulty pressure sensor cause these symptoms or is the turbo lag pointing more definitively towards the wastegate

4 comment(s)

manuellehmann6

Those symptoms do sound like a boost leak or wastegate issue I had similar problems on my old Renault Megane though it was a petrol engine Reduced power check engine light and a whistling sound were the main culprits Have you checked for any obvious cracks or leaks in the hoses connected to the turbo A split hose can cause all sorts of boost-related problems It could also be the pressure sensor giving false readings but my bet is on the wastegate sticking Did you notice any turbo lag before this started

richardhunter1 (Author)

I appreciate the input I did a visual inspection of the hoses but I didn't find anything obvious How did you ultimately diagnose the wastegate problem on your Megane Was it throwing specific codes or did you have to do more in-depth testing to confirm it I'm trying to avoid just throwing parts at it but the symptoms are getting worse

manuellehmann6

The Megane was throwing a 'turbo underboost' code but the mechanic also noticed the wastegate actuator arm was sticking He disconnected the arm and could feel the resistance It sounds like you are experiencing something similar Given your symptoms I'd suggest getting it checked out at a workshop They can pressure test the system and properly diagnose the problem Could save you money in the long run

richardhunter1 (Author)

Thanks for the insight I took it to a workshop and they confirmed the wastegate valve was defective The total repair cost was 860€ Appreciate your help in narrowing down the possibilities

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