Patent ID: 8156728

Claim:
A method carried out during operation onboard in a vehicle for diagnosing of at least a part of an exhaust emission control system, arranged in a vehicle with a combustion engine that, during operation, emits exhaust gases to the exhaust emission control system, which exhaust emission control system comprises at least one NOx-reducing catalyzer that can be regenerated, and a predetermined quantity of reductant is added to the exhaust emission control system upstream of at least the NOx-reducing catalyzer, for at least a predetermined interval of time, for regeneration of the NOx-reducing catalyzer and a drop in pressure across the NOx-reducing catalyzer is measured, which method comprises: carrying out a first measurement and recording of a first measured value for the drop in pressure at a point in time immediately before the reductant is added to the exhaust emission control system; carrying out a second measurement and recording of a second measured value for the drop in pressure at a point in time after the completion of the regeneration; comparing the first and second values, and carrying out a deSOx if an increase in the drop in pressure between the first and second measured values is less than a first predetermined value.