Display group 33 -Oxygen sensor control- Oxygen sensor control values

Fig 1: Identifying Display Group 33 - Oxygen Sensor Control (Oxygen Sensor Learned Values)

Courtesy of VOLKSWAGEN OF AMERICA, INC.

Display Group 33 - Oxygen Sensor Control (Oxygen Sensor Learned Values)

• For Evaluation 1 in Fig 1, see EVALUATING DISPLAY GROUP 33, DISPLAY ZONE 1 - OXYGEN SENSOR CONTROL BEFORE CATALYTIC CONVERTER .
• For Evaluation 2 in Fig 1, see EVALUATING DISPLAY GROUP 33, DISPLAY ZONE 2 - OXYGEN SENSOR VOLTAGE OXYGEN SENSOR BEFORE CATALYTIC CONVERTER .

Notes on display zone 1:

• The display must fluctuate around 0. If constant 0 is displayed, the Oxygen sensor control has switched from regulation to control, because there is a malfunction in the Oxygen sensor control. Check DTC Memory. See Diagnostic Trouble Code (DTC) memory .

Notes on display zone 2:

• The voltage signal "rich mixture (low level of residual oxygen)" is approx. 0.7 to 1.0 V.
• The voltage signal "lean mixture (high level of residual oxygen)" is approx. 0.0 to 0.3 V.
• When changing from "rich" to "lean" and back again (LAMBDA = 1.0) the voltage jump will change from 0.7 to 1.0 V to 0.0 to 0.3 V or back again.
• Due to the steep voltage jumps the Oxygen sensor control cannot keep the ideal mixture composition LAMBDA = 1.0 constant. The control fluctuates constantly between conditions "slightly too lean" and "slightly too rich".

Oxygen sensor voltage U "LAMBDA" in mV 

A: High Oxygen sensor voltage

• Rich mixture (excess of fuel or shortage of air)
• Higher CO value

B: Low Oxygen sensor voltage

• Lean mixture (shortage of fuel or excess air)
• Lower CO value
  Fig 2: Identifying Oxygen Sensor Voltage Graph

  Courtesy of VOLKSWAGEN OF AMERICA, INC.