(DME) Condition For Fault Memory Entry - 1
29F4 - P0420Information saved in
DME
Fault code
29F4 - P0420
Fault text
Catalytic-converter conversion
Fault description
Catalyst System Efficiency Below Threshold (Bank 1)
Condition for fault identification
Test condition:
Provisional data: Unsatisfactory suitability for conversion
detected.
Speed >0 and < 160 km/h
catalytic converter temperature
(Model) > 380 °C
Lambda control and trim control = ON
Engine speed between 1500-3500 rpm
Terminal condition: Terminal 15, engine on
Voltage condition:
Voltage in onboard electrical system > 10 V
Condition for fault memory entry
No time debounce, instead standard lambda control
periodicity
Action in service
1. Visual inspection of catalytic converter
- Physical damage?
- Is extreme discoloration present on the converter?
(gentle reddish-blue hue is normal, especially after high-
speed highway operation).
2. Leak check embracing entire exhaust system
Seal leaks and conduct road test
3. Remove O2 sensors and visually inspect for particles,
extreme discoloration, catalytic converter residue
visual inspection through sensor holes in catalyst matrix as
indicated.
4. If O2 sensor malfunction is suspected: Consider replacing
O2 sensor
(Did any known sensor faults or malfunctions occur prior to
the catalyst fault entry being registered?)
5. Replace catalytic converter for the affected bank
Fault effect and breakdown warning
Driver information
Warning light:
MIL on in 2nd driving cycle
Service instruction
none