O2 sensor signals (G3/3 to G3/6), electrical fault | ||
1A | Fault code ( Readout on generic scan tool) | P200F Right O2 sensor upstream of TWC (G3/4) (P0130) P2010 Right O2 sensor downstream of TWC (G3/6) (P0136) P2082 Left O2 sensor upstream of TWC (G3/3) (P0150) P2083 Left O2 sensor downstream of TWC (G3/5) (P0156) |
1B | Engines 112, 113 as of 1/01 Fault code ( Readout on generic scan tool) | P200F-[1] Right O2 sensor upstream of TWC (G3/4), short circuit to positive (P0130) P200F-[4] Right O2 sensor upstream of TWC (G3/4), discontinuity (P0130) P200F-[8] Right O2 sensor upstream of TWC (G3/4), short circuit in the signal line (P0130) P2010-[1] Right O2 sensor downstream of TWC (G3/6), short circuit to positive (P0136) P2010-[4] Right O2 sensor downstream of TWC (G3/6), discontinuity (P0136) P2010-[8] Right O2 sensor downstream of TWC (G3/6), short circuit in the signal line (P0136) P2082-[1] Left O2 sensor upstream of TWC (G3/3), short circuit to positive (P0150) P2082-[4] Left O2 sensor upstream of TWC (G3/3), discontinuity (P0150) P2082-[8] Left O2 sensor upstream of TWC (G3/3), short circuit in the signal line (P0150) P2083-[1] Left O2 sensor downstream of TWC (G3/5), short circuit to positive (P0156) P2083-[4] Left O2 sensor downstream of TWC (G3/5), discontinuity (P0156) P2083-[8] Left O2 sensor downstream of TWC (G3/5), short circuit in the signal line (P0156) |
2 | Fault storage Actuation of the engine diagnosis indicator lamp (EURO3/4) or CHECK ENGINE (MIL) malfunction indicator lamp | after expiry of test duration and fault following two successive driving cycles with faults |
3 | Checking frequency | Continuous |
4 | Checked signal or status | Limits for O2 sensor signal |
5 | Fault setting conditions Lower limit value Upper limit value Plausibility |
Voltage must not be less than 0.06 V (model 170: 0.015 V). Voltage must not be greater than 1.5 volts. After 3 seconds of deceleration fuel shutoff the voltage must be no greater than 0.2 V. |
6 | Check prerequisites | - lambda controls enabled - no fault in O2 sensor heater - no high loading of activated carbon filter (lambda greater than 0.4) - no CAN fault |
7 | | After conducting tests the following electrical connection faults for the O2 sensors upstream of TWC and downstream of TWC are recognized: line discontinuity, short circuit and shunt (high ohm short circuit) to ground or battery voltage. The following supplemental information is stored together with every fault code: - line for O2 sensor signal has a shunt or limited voltage increase of the O2 sensor signal. - discontinuity on O2 sensor signal ground. - on a cold O2 sensor a shunt to +12 V or to ground for the ME control unit. If there is a short circuit of the O2 sensor ground to +12 V the ME control unit will be destroyed! |
P07.61-2531-11
Sensor counter voltage
shown for engine 137 on a O2 sensor
G3/11 Left O2 sensor downstream of TWC for cylinders 7-9
Connector
1 Sensor heater circuit 87
2 Sensor heater ground
3 Sensor signal ground
4 Sensor signal (about 0.45 V at λ = 1 and a O2 sensor at normal operating temperature)
N3/10 ME control unit
4x Measuring amplifier for analysis circuit for sensor signal and sensor signal ground
0.268 V Counter voltage based on ground (circuit 31)
Z6/4 Ground connector sleeve (sensor downstream of TWC)
Z7/36 Circuit 87M2e connector sleeve
The ground for the sensor signals at the ME control unit is raised to approx. +0.268 V compared to the general vehicle ground. The analysis circuit for the O2 sensor signal outputs this so-called sensor countervoltage of approx. 0.268 V. If the 02 sensor is cold, the sensor internal resistance (Nernst cell) is so high, that the O2 sensor voltage is initially equal to the countervoltage irrespective of the mixture composition.
Check of the countervoltage allows line discontinuity, short circuit and shunt (high ohm short circuit) to ground or battery voltage to be recognized.
If there is a short circuit of the sensor signal against ground or the removed O2 sensor, the ME control unit switches the lambda control to open-loop operation (medium λ value about 450 mV). This prevents a high fuel consumption.