Diesel diagnostics

Electronic Engine Control Sensors

Actuators

Ignition Systems

Complex Engine Diagnostics

CSS script documentation

Px script documentation

ElPower script documentation

Software

O2 Sensor

The Zirconia Lambda sensor which is by far the most common narrow band sensor is used to determine the air/fuel ratio in the combustion chamber by reading the oxygen demand of the residual exhaust gas. The sensor tip is made of catalytic material, is hot, and is subject to hot exhaust gas. This exhaust gas may contain some unburned or partially burned fuel if the air/fuel ratio in the combustion chamber is “rich”. To complete the combustion of the unburned or partially burned fuel in/at the catalytic material at the hot sensor tip, additional oxygen is needed. This additional oxygen travels through the membrane at the sensor tip and causes a potential (voltage) difference to develop. This voltage potential is then read by the computer and interpreted as a rich condition. If the air/fuel ratio in the combustion chamber is “lean”, no additional oxygen is needed and a voltage potential does not develop. This low voltage condition is interpreted by the computer as a lean condition.

O21
Oxygen Sensor

A very rare sensor is the Titania sensor. This sensor is a true oxygen sensor and it varies it’s resistance according to the oxygen content in the exhaust stream.

The sensors can be mounted before as well as after the catalytic converter.

Application:

  • narrow band lambda sensor
  • wide band lambda or air/fuel ratio sensor
Oxygen sensor location on KIA Ceed 1.6L
Typical location of the oxygen sensor
Connection to an Oxygen sensor
Connection of the USB Autoscope IV to the sensor signal wires
CKP-mode
Setting the USB Autoscope IV to view the signal from the oxygen sensor
Output voltage waveform from a conventional narrow band O2-sensor “Zirconia”
Output voltage waveform from a conventional narrow band O2-sensor “Zirconia” or zirconium dioxide in good condition on Opel Vectra C 2.2 2006, recorded while the engine was at idle
Output voltage waveform from a conventional narrow band O2-sensor “Zirconia”
Output voltage waveform from a conventional narrow band O2-sensor “Zirconia” or zirconium dioxide with a very slow reaction rate. The waveform was recorded while the engine was at idle
Output voltage waveform from a conventional narrow band O2-sensor “Zirconia”
Output voltage waveform from a conventional narrow band O2-sensor “Zirconia” or zirconium dioxide in good condition on a car in bad condition (injectors are very dirty), recorded while the engine was at idle
Output voltage waveform of the “Titania” or titanium dioxide O2-sensor in good condition
Output voltage waveform of the “Titania” or titanium dioxide O2-sensor in good condition, recorded while the engine was at idle

The distortions of the output signal of the O2-sensor from the bank 2 cylinders are caused by uneven air/fuel ratios in the various cylinders in this group

Output voltage waveforms from a properly functioning zirconia narrow band lambda-sensor and power supply sensor heater
Output voltage waveforms from a properly functioning zirconia narrow band lambda-sensor and power supply sensor heater
2-3

  • 1 – signal from a lambda sensor mounted before the catalytic converter

  • 2 – the power supply for the sensor heater

  • A – engine start

  • B – running at idle; the sensor is not hot enough to function properly

  • C – the sensor is hot enough to start working

  • D – start of smooth throttle valve opening

  • E – closing of throttle valve

3-3
Engine running at idle
4-3
Engine running at high RPMs
5-3
Output voltage waveforms from a properly functioning zirconia narrow band lambda-sensor and power supply sensor heater
6-3

  • 1 – signal from lambda-sensor mounted before the catalytic converter

  • 2 – PWM control signal for the the sensor heater

  • A – engine start and running at idle

  • B – the engine control unit increased the duty cycle of the sensor heater

  • C – the sensor is heated sufficiently to work properly

  • D – start of smooth throttle valve opening

  • E – closing of throttle valve

7-3
Engine running at idle
9-2
Engine running at high RPMs
8-2
Engine running at high RPMs
10-1
Output voltage waveforms from a properly functioning zirconia narrow band lambda sensors
11-1
Engine running at idle

  • 1 – signal from lambda-sensor mounted before the catalytic converter

  • 2 – signal from lambda-sensor mounted after the catalytic converter

  • A – engine start and running at idle

  • B – start of smooth throttle valve opening

  • C – closing of throttle valve

12-1
Engine running at high RPMs
13-1
Sharp throttle closing at 3000 RPM
14-1
Output voltage waveform from a malfunctioning lambda-sensor mounted before the catalytic converter. The reaction rate of the sensor is very slow, signal amplitude is low

  • A – engine start and running at idle

  • B – sensor heated and starts to work

15-1
Engine running at idle
16-1
Sharp throttle closing at 3000 RPM
17-1
Output voltage waveform from a malfunctioning zirconia narrow band lambda-sensor. The sensor is not working

  • A – engine start and running at idle

  • B – start of smooth throttle valve opening

  • C – deceleration and running at idle

  • D – snap throttle

18-1
19-1
Output voltage waveform from a malfunctioning lambda-sensor. The malfunction causes the sensor to output a negative voltage

  • A – engine running at idle

  • B – turning off the fuel injectors during deceleration after snap throttle

  • C – turning on the injectors at the end of deceleration

20-1
Typical output voltage waveform from a properly functioning narrow band titanium oxide lambda sensor

  • A – engine start

  • B – sensor heated and starts to work

21-1
Engine running at idle
22-1
Engine running at high RPMs
23-1
Voltage waveforms from wires of wide band lambda sensor BOSCH LSU (VW Golf 1.6 2003)
24-1

  • 1 – black wire

  • 2 – yellow wire

  • 3 – red wire

  • 4 – calibration resistor

  • 5 – white wire

  • A – engine start and running at idle

  • B – snap throttle

  • C – deceleration

  • D – engine shut off

25-1
Voltage waveform of the measurement cell and current of the pump cell of wide band lambda sensor BOSCH LSU, received in differential measuring mode

  • 1 2 – output voltage of the measurement cell

  • 3 4 – voltage drop on calibration resistor of the sensor

Video

Waveform examples