This Mercedes limps with NO fault codes. Here's what the last tuner did.

A Mercedes in limp mode, ZERO fault codes on every scan tool, and a DPF that won't regenerate. We pull the ECU file apart and show you exactly what the previous tuner left behind and why it's causing all of it. This is a real customer file from a Delphi CRD3 ECU. Someone carried out an AdBlue delete and a batch of DTC removals, but they did it wrong. All four EGT sensors are reading 0°C due to corrupted linearisation tables, a stack of unrelated fault codes have been blanket-disabled, and P0088 (fuel rail pressure) has been partially suppressed in a way that hides the code from every diagnostic tool but leaves the limp mode reaction fully armed. We walk through every finding and explain exactly how these ECU fault records work, and why half-done DTC removal is often worse than doing nothing at all. If your vehicle is in limp mode with no stored fault codes, the answer may not be on the scan tool. It may be in the file. In this video: Why "no fault codes" doesn't mean nothing is wrong. How DTC records work inside the ECU - detection, storage, and reaction as separate stages. What flattened EGT linearisation tables look like and what they do to the engine. The difference between a properly neutralised DTC and a half-disabled one and why P0088 was causing limp mode while staying invisible to diagnostics.