Method for diagnosing an exhaust gas cleaning system of a lambda-controlled internal combustion engine

US6799419B2 · kind B2 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Gerd Rösel · Dresden, DE
• Hong Zhang · Tegernheim, DE

Key dates

• Filing date: Oct 9, 2002
• Grant date: Oct 5, 2004
• Expiry date: Oct 18, 2022

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T10/40
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A method for diagnosing an exhaust gas cleaning system of a lambda-controlled internal combustion engine where a catalyst is subjected to a specific oxygen load which is greater than the normal operating load, by increasing the surface covered by the oscillation of a signal of a pre-catalyst lambda probe according to a set value. The exhaust gas cleaning system can be tested by evaluating the oscillation of a signal of a post-catalyst lambda probe. In the event this diagnosis shows a defect in the exhaust gas cleaning system without the area covered by the oscillation of the probe signal of the pre-catalyst lambda probe having had to be increased to or beyond a set value, the pre-catalyst lambda probe is defective. Otherwise, it can be concluded that the catalyst is defective.