Well said Jon.

it winds me up that these "re-mappers" delete codes and muck up live data, when it goes wrong trying to diagnose a fault can be such a nightmare.

we had a vectra v6 diesel, clean car, in for a lack of power, customer told us its been dpf deleted and remapped. live data made no sense, no codes stored or could be created unplugging sensors. in the end i recommended a new ecu flashed to latest standard software and a new dpf BEFORE further diagnosis.

saying this to a customer could make a good tech look stupid in untrained eyes