#diesel
8 posts in Car Diagnostics blog about "diesel" — OBD-II diagnostics, DTC codes, repair. ← All posts
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EGR valve and EGR cooler leak: codes P0401, P0402, P0404 and why diesel Passat/A6 "got sooted up"
How to diagnose EGR via OBD-II: difference between P0401 (low flow) and P0402 (high), EGR cooler leak, why "EGR delete" is a short fix with long problems.
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AdBlue (DEF): SCR system diagnostics, common faults and how to avoid a locked-out engine
What AdBlue/DEF is, how OBD-II sees the SCR system, codes P204F, P20E8, P229F, why a Euro 6 diesel stops starting after 5 tries with an empty tank, and how to diagnose NOx sensors.
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Diesel glow plugs: codes P0670-P0674 and why "cold start" stops working
What glow plugs are, how OBD-II sees their state via P0670, P0671-P0678, why one dead plug ruins the whole cold start, and how much replacement costs on a 4-cyl diesel.
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Diesel injector coding: correction values, EDC17, and when an injector needs a new code
What IMA/injector correction code is, how EDC17 ECU learns each injector, codes P0263-P0272, what OBD-II reads, and why "just replace the injector" on diesel doesn't work.
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DPF (Diesel Particulate Filter): diagnosing regeneration, clogging and when it's time for a clean
What a DPF is, how it regenerates, which DTCs signal a problem (P2002, P244A, P244B), how to read soot levels via OBD-II, and why short trips kill diesel engines.
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Forced DPF regeneration via scan tool: step-by-step for VW, BMW, Mercedes
When passive/active DPF regen fails: how to run forced/stationary regen via VCDS, ISTA, Xentry or universal Autel. Safety, time, warnings.
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Turbo diagnostics: P0299 (underboost) and P0234 (overboost) — 8 causes
How OBD-II sees the turbocharger: codes P0299, P0234, P0045, P0046. MAP sensor, VGT actuator, waste gate. Why turbos "die" and what to do about that side whistle.
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Diesel Engine Power Loss: 10 Causes and Step-by-Step Diagnosis
Why a diesel car does not pull, how to quickly distinguish turbo, EGR, DPF or injector issues, and which DTC codes to read first.