Fault code description - three-way catalytic converter effect too low

AD07.61-P-4000-16A

Fault code description - three-way catalytic converter effect too low



1

Fault code

 right

 left

2

Fault storage

Actuation of the engine diagnosis indicator lamp (EURO3/4)

or CHECK ENGINE (MIL) malfunction indicator lamp 

after expiry of test duration and fault

after two successive driving cycles with faults

3

Checking frequency

continuous

4

Checked signal or status

Voltage ratio (amplitudes) of oxygen sensor signal downstream of TWC to oxygen sensor signal upstream of TWC

5

Fault setting conditions

Limit value

Checking duration

The amplitude of the O2 sensor signal downstream of TWC may not exceed a maximum of 75% of the amplitude of the O2 sensor signal upstream of TWC ca. 170 s

6

Check prerequisites

- Engine speed 1000 to 2700 rpm

- Load approx. 22 % to 52 %

- Catalyst temperature > 380 °C

- Lambda control enabled and Lambda > 0.4

- No fault in O2sensor heater or aging

- Air pressure more than approx. 780 hPa (i.e. no test is performed above a height of
approx. 2500 m)

7



After a repair, carry out tests and driving instructions

The tests 1 to 4 must be carried out together one after the other without switching off the engine.

1st Check O2sensor heater

Vehicle is stationary and in drive position P

Coolant temperature > 80 °C

Let engine run at 2000 up to 2500 rpm for approx. 2 minutes

Then let engine run in idle for approx. 6 minutes

2nd Check aging of O2 sensor upstream TWC [KAT]

Drive vehicle in drive mode D for approx. 3 minutes at approx. 70 km/h on a straight road

3rd Check catalytic converter effect

Drive vehicle in drive mode D for approx. 3 minutes at approx. 80 up to 90 km/h on a straight road

4th Check self-adaptation of mixture formation.

Vehicle is stationary and in drive position P

Let engine run in idle for approx. 3 minutes

If the individual test is performed, this is displayed in the HHT as follows: If the test is passed without a fault, "-V-" is placed in dark (repair is successful). If the test is passed with a fault, "-F-" is placed in dark. After ignition OFF the tests are again restored (white field). Only after the test has been perfomed once again, the corresponding fields are once again placed in dark.

Carry out a new test only after approx. 10 seconds ignition OFF.

8



The three way catalytic converter is evaluated on the basis of its ability to store oxygen. Several measurements must be performed in the specified engine speed and load range. The results are compared with a map and a fault is detected in this way.

The amplitude of the O2sensor voltage downstream TWC must be less than the amplitude of the O2sensor voltage upstream TWC (Note: If e.g. no monolith was built into the catalytic converter, the O2sensor signals upstream TWC and downstream TWC would be identical).

If the fault codes for the three-way catalytic converter and for the oxygen sensor upstream of TWC are output simultaneously, first replace the oxygen sensor upstream of TWC.

If then a TWC fault is no longer detected, and if the effect of the three-way catalytic converter has been slightly reduced, it does not need to be replaced yet.