Good evening, this week my audi A3 1.6 8L gasoline October 2002 got a number of malfunctions in the engine management.

After the timing belt has been replaced last week its seemed to occur.

The mechanic did a management reading, said that the first four errors (out of 5) had to do with the plugs he had to unplug in case of the timing belt replacement. The fifth error was a new disturbance which indicated that the lambdasonde did not function well (before the cat). This lamdasonde I replaced myself using an original Bosch sonde of the same type.

Now I have five/six errors in my car management.

I did reset my managment computer a couple of times but the errors keep coming back.

It concerns the following failures:

Current Fault P0418 Secondary Air Injection System Relay 'A' Circuit Malfunction
Current Fault P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
Current Fault P0102 Mass or Volume Air Flow Circuit Low Input
Pending Fault P0140 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
Pending Fault P0037 HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
Pending Fault P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted

Got the car examined in the garage this afternoon.
The mechanic told me that it seems there is an electrical failure in the wiring because of the several different errors at the same time, indicating again the lambdasensor and the air pump. The mechanic checked the air pump and found it to be ok.

I think one single sensor causes the different error messages, the question is which sensor?

Where should I look? What should I check first, in what order?

Annex: The reading of the universal garage

Like to hear your opinion

Thanks in advance!

Greet Eike