Oxygen sensor heating, fault code description ME-SFI - AD07.61-P-4000-08A

1	Fault code	P0135 on right upstream of TWC P0141 on right downstream of TWC (not for model 463) P0155 on left upstream of TWC P0161 on left downstream of TWC (not for model 463)
2	Fault storage	after expiry of test duration and fault
2	Actuation of the engine diagnosis indicator lamp (EURO3/4) or CHECK ENGINE (MIL) malfunction indicator lamp	after two successive driving cycles with faults
3	Checking frequency	continuous
4	Checked signal or status	Calculated resistance value for sensor heating
5	Fault setting conditions	< 2.0 Ω (corresponds to approx. 6 A at 12 V)
	lower limit value	> 10 Ω (corresponds to approx. 1.2 A at 12 V)
	upper limit value	Fault in oxygen sensor heating is also set if the cycle duration of the oxygen sensor signals within a driving cycle suddenly increases to more than 25 s.
6	Check prerequisites	engine running Coolant temperature > 80 °C sensor heating ON and heating-up time of approx. 220 s elapsed 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 O ₂ sensor 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 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 performed once again, the corresponding fields are once again placed in dark. Carry out a new test only after approx. 10 seconds ignition OFF.