Bylund Automotive Support

i assembled the Lambda shield system and as a precaution i used first a non generic LSU 4.9 clone i bought from Germany in case there is a wiring mistake that could damage the sensor.

The shield works on the bench as expected showing sensor heater worming followed by a display of all expected parameters for about two seconds including an O2 of about 20% then jumping back to sensor heating repeatedly for over an hour.

the sensor is hot to touch
the heater supply voltage was checked externally with a voltmeter and found well within 12 volt, stable and matching the system display
the sensor is not Bosch genuine, this what i am going to test next.

have anyone seen this problem before?
any suggestions?

Hello Rasheed,

What is most likely happening is that you are receiving an error from the CJ125 causing the device to reset and start the heating phase over and over again. This can be caused by a faulty supply but as you have already verified that it works that is not the issue.

Second this is a typical issue with aftermarket sensors "stuck in heating". You can discard these errors by always letting the COM_SPI() function return CJ125_DIAG_REG_STATUS_OK (0x28FF) for diagnosing the problem.

But I only recommend using genuine Bosch LSU 4.9 sensors.

thanks for the prompt response.
i would rather try to retest with the genuine probe than disable the Diagnostics functions which are an alarm.
i will test with genuine sensor and confirm.
thanks again.

The Bosch sensor is functioning steady showing IP of 2.4 mA, O2 of 19.98 ? and a steady green dot
but no Lambda and no AFR figures just dashes.
is this the way it supposed to be?

how can i display the AFR and the Lambda ?

RasheedDEC wrote: ↑

19 Aug 2020 21:19

The Bosch sensor is functioning steady showing IP of 2.4 mA, O2 of 19.98 ? and a steady green dot
but no Lambda and no AFR figures just dashes.
is this the way it supposed to be?

Rasheed,

That sounds correct!

The green indicator means it is measuring.
Yellow indicator means it is heating.
Red indicator means that the power is low, missing sensor or any other error.

When measuring in free air like you are doing now there is no point in converting it to a lambda value. Most lambda measurements read up to λ9.99. Therefore you only see the Oxygen content in %. Typically 20-21% but if you are using a fresh sensor they usually measure a little low until they have been running at the correct temperature for a couple of hours. For automotive applications this is not an issue.

Are you using the X7 jumper so you have a stable 5V or are you powering the Arduino of the USB? - See below video for some hints.
https://www.youtube.com/watch?v=YBFQFQDi_Lo
This will especially affect the accuracy at free air.

RasheedDEC wrote: ↑

19 Aug 2020 21:19

How can i display the AFR and the Lambda ?

Simply breath on the sensor and you will see the values changing and it will display both Lambda and AFR. If you do not want to use a flame on the sensor you can use the gas from a cigarette lighter effectively.

i am surprised and appreciating how quickly i got the response to my concerns. thank you

very logical explanation for omitting the AFR and Lambda in free air measurement, i am using a brand new Bosch LSU 4.9 out of the box.
i will add a note about that in the Bosch vs. generic oxygen sensor topic

i am collecting your recent notes of the display and your notes about the GUI and the example code in my own personal Technical manual.
eventually i am planning to share it with the new members who are not yet familiar with these system when there is enough of it.

as a safety precaution, i decided as a rule not to use the X7 jumper and to use two independent power sources, A 6 volt power source as i realized that the Arduino has a 5 volt regulator and a 12 volt 1 A power source for the sensor heater.

RasheedDEC wrote: ↑

20 Aug 2020 05:50

i am surprised and appreciating how quickly i got the response to my concerns. thank you

Great, so with the Bosch sensor everything is now working correctly?

RasheedDEC wrote: ↑

20 Aug 2020 05:50

as a safety precaution, i decided as a rule not to use the X7 jumper and to use two independent power sources, A 6 volt power source as i realized that the Arduino has a 5 volt regulator and a 12 volt 1 A power source for the sensor heater.

The only risk of using the X7 jumper would be if you accidently connect two different power sources at once in the two DC-jacks. USB is no issue. If you connect via the Arduino DC jack or with the X7 connector, both feed VIN and the voltage regulator can handle up to 20V according to the specification from Arduino. You can actually power the shield from the DC-jack on the Arduino with the X7 jumper as well, however it is not recommended due to the 1A rating of the input diode of the Arduino.