Patent ID: 7418853

Claim:
Process for diagnosis of a lambda probe associated with an exhaust gas catalytic converter of an internal combustion engine, said process comprising: measuring respective time delays (Δt 1 and Δt 2 ) until a sudden change in a lambda signal (λ a ) upstream from the exhaust gas catalytic converter appears for the lambda signal (λ b ) of the lambda probe associated with the exhaust gas catalytic converter for a known first and second exhaust gas mass flow {m 1 , m 2 } through an exhaust gas catalytic converter, and determining, based on the measured time delays (Δt 1 , Δt 2 ), how large a catalytic converter-induced portion (Δt cat1 , Δt cat2 ) which is dependent on the exhaust gas mass flow ({m 1 , m 2 }) is and how large a probe-induced portion (tΔ probe1 , Δ tprobe2 ) of the time delays (Δt 1 , Δt 2 ) which is essentially independent of the exhaust gas mass flow ({m 1 , m 2 }) is, the probe-induced portion (Δt probe1 , Δt probe2 ) being used as a diagnosis criterion for the lambda probe.