Spartan 3 ADV Outputs Constant AFR

Spartan 3 ADV outputs constant 14.6-14.7 AFR on MegaSquirt 3 CAN-bus and 14Point7 Gauge. Was working before. Bad sensor? Any ideas to try?


I would like to add that the red warning light is on for the gauge even though AFR is within the acceptable bounds.

does the sensor heatup?

Hi Alan, the sensor does heat up. I connected my replacement sensor I got from you and have the same readings from my CAN-bus and analog AFR signals. Perhaps the controller reset and is not reading the O2 sensor?

I need to check the settings anyways, the sensor I took out is not even an LSU ADV. Bosch 0258027157 is what it was using before. Looks like it should be a 0258027010 but I didn’t have a chance to read the one you sent me.

Can you PM me with your order number?

PM’ed. To be clear the 157 sensor is what I’ve had in the car for 2 years, but I don’t remember if I got it from you or someone else.

I was experiencing the same issue where sometimes I would get an AFR output (Linear and CAN) and sometimes I would not. I updated the Spartan 3 you sent me to Firmware 1.04.

I checked my PayPal order and know it should be an LSU ADV sensor but now I can’t get an AFR output at all. When I set the Spartan 3 to “LSU 4.6” mode it connects every time and appears to give correct output. How can I verify which sensor I have?

The ADV sensor has a short 8.5 inch grey cable between metal sensor head and the sensor connector. The LSU 4.9 has a much longer black cable, it also has “LSU49XX” etched on the metal sensor head.

Looks like I have the grey cable (ADV), no serial number etched that I can see. So now the question is why does it not read input under ADV mode and only under 4.9 mode? What is the difference between the modes, is running on 4.9 mode with an LSU sensor output an incorrect reading?

If the wrong type is selected the readings are not correct.

There are separate circuits for the LSU 4.9 and the ADV, each circuit is switched on or off based on the sensor type selected.