clarakrause64
Peugeot 407 Boost Pressure Fault
Summary of the thread
A 2007 Peugeot 407 with a diesel engine experienced a boost pressure control fault, leading to reduced engine power, poor response, and increased fuel consumption. The issue was initially suspected to be caused by a defective pressure sensor. However, further discussion suggested that a faulty vacuum switching valve could also be responsible. A workshop diagnosis confirmed the vacuum switching valve defect, and its repair resolved the problem.
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4 comment(s)
clarakrause64 (community.author)
I have not detected any hissing sounds. The engine is indeed sluggish at low RPMs, exhibiting noticeable turbo lag. Could a defective vacuum switching valve also cause these issues, in addition to a faulty pressure sensor?
heinz_jung1
A vacuum switching valve issue is certainly plausible and could mimic the symptoms of a faulty pressure sensor. Considering the turbo lag and lack of hissing, it might be the more likely culprit. While diagnosing it yourself is possible, a workshop visit might save you time and potential misdiagnosis.
clarakrause64 (community.author)
Based on your assessment, I took the vehicle to a workshop. The diagnostic confirmed a defect in the vacuum switching valve. The repair cost 140€, resolving the boost pressure control fault.
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PEUGEOT
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407
heinz_jung1
Those symptoms definitely point to a boost issue. Have you noticed any unusual noises, like a hissing sound, when the turbo is supposed to be spooling up? A pressure drop could also be caused by a leak in the intercooler piping. Does the engine feel particularly sluggish at low RPMs?