P0401: meaning, causes and solutions
Fault code P0401: Insufficient exhaust gas recirculation flow. Symptoms, real causes and how to fix it. MasterTuning diagnosis throughout Italy.
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Diagnostic guides and OBD fault codes explained: symptoms, causes and what to do, from the MasterTuning workshop.
116 articles
How much does ECU remapping cost and what results to expect
ECU remapping: indicative costs, real power and torque gains, what affects the price and what to be wary of. MasterTuning.
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Faulty crankshaft sensor: symptoms and why the car will not start
Faulty crankshaft sensor: symptoms (no start, stalling, rev counter at zero), causes, how to test it and how much it costs to replace.
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Faulty AdBlue pump: symptoms, faults and no-start countdown
Faulty AdBlue pump or SCR system failure: messages, remaining-starts countdown, reduced power. Causes, what to do now and why not to wait.
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Faulty MAF sensor: symptoms and quick test
Faulty or dirty MAF sensor: loss of power, black smoke, consumption, P0100-P0103. The quick test by unplugging it, cleaning or replacing, and cost.
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Timing belt or chain: when to change it
Belt or chain timing drive: real intervals, wear symptoms (noise, timing faults) and what you risk if it breaks. MasterTuning advice.
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Worn dual-mass flywheel: noises and symptoms to recognise
Worn dual-mass flywheel: noise at idle and on switch-off, vibration, causes and when to replace it. Professional check by MasterTuning.
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Slipping clutch: symptoms and when to replace it
Slipping clutch: how to recognise it with a practical test, causes of premature wear and what to replace together. MasterTuning advice.
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Worn-out glow plugs: symptoms and how they are tested
Failed glow plugs on diesels: symptoms (hard cold starting, smoke, preheat light), testing and replacement without breaking them. MasterTuning.
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Faulty injectors: symptoms and tests to identify them
Faulty diesel injectors: rough idle, hard starting, smoke, consumption. The tests that matter (return flow, delivery, corrections) and why not to change them all.
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Failed turbocharger: symptoms, causes and how to avoid breaking it
Failed turbo: symptoms (loss of power, smoke, whistle), real causes (oil, variable geometry) and how to prevent failure. MasterTuning.
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Dirty throttle body: symptoms and cleaning with adaptation
Dirty throttle body: unstable idle, jerking, car stalling. How it is cleaned, why adaptation is needed and what it costs.
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