VW Beetle code scan question about 02 sensors

[Stephen Bowen]

Trying to work out a possible P0420 error and attempting to figure out the o2 sensor data.

For some reason, the scan tool–using ‘live data’ (as opposed to dead data??) It shows on this 4 cylinder engine the bank 2 sensor which is likely the one after the converter–shows that one in voltage. And for the bank 1 sensor? The only information it shows is “Current Flow”?? I’ll cut and paste one frame and see if it makes sense to anyone:

Live Data
Number of DTCs stored in this ECU 1
Fuel system 1 statusCL
Fuel System 2 status–
Calculated LOAD Value(%)20.4
Engine Coolant Temperature(¡£C)93
Short Term Fuel Trim -Bank 1(%)-2.3
Long Term Fuel Trim – Bank 1(%)9.4
Engine RPM(rpm) 2731
Vehicle Speed Sensor(km/h)90
Ignition Timing Advanece for #1 Cylinder(¡£)27.5
Intake Air Temperature(¡£C)-4
Air Flow Rate from Mass Air Flow(g/s)14.00
Absolute Throttle Position(%)10.2
Commanded Secondary Air StatusOFF
Location of Oxygen SensorsB1S12–B2S—-
Oxygen Sensor Output Voltage Bank 1-Sensor 2(V)0.630
Short Term Fuel Trim Bank 1-Sensor 2(%)N/A
OBD requirements to which vehicle is designedOBD&OBDII
Equivalence Ratio (lambda)(Bank 1-Sensor 1)1.008
Oxygen Sensor Current(Bank 1-Sensor 1)(mA)0.016

I had the wife drive down to my local mall for the ‘walking’ bit (I’m still trying to recover from a blown out heart attack a few years ago…so walking is my best workout) While she was driving? I was recording the live data–and I did select ‘all’ for the scan tool. So pretty much everything the scan tool could get out of the car’s computer? Is listed above for one frame. I know the fuel trim is not great for long term. (trying to work out one detail at a time….)

Just not sure if this is something VW does to screw with people–or if there is a way to ‘read’ that output current and come up with something easier to work with. The car of course is a 2001 VW New Beetle with a 2.0 standard. Engine is a AVH code type.

Thanks all!

S-

Topic

[sam priem]

The o2 sensor that has current flow readings is a wide range o2 sensor. instead of the old fashioned o2 sensor that uses a signal voltage between 0-1 volt to tell the computer how rich/lean the engine is running, wide range o2 sensors use current(amps in the sensor circuit, not exhaust current). A rich condition will cause a negative current, and lean condition will cause a positive current, and at stoichiometry (air fuel ratio at 14.7:1) there is no current. the amount of current in either direction dictates how rich/lean the engine is running. in your case, the reading on your scan tool is telling you the vehicle is running lean. the fuel trim and lambda readings agree.

[Author]

Replies