Fuel system 1 status

Resistolcowboy · Post by **Resistolcowboy** » 25 Apr 2019, 00:46

Closed loop, using at least one oxygen sensor but theres a fault in the feedback system. this fault happens only at 1500 RPM and lower, then will go into closed loop, using oxygen sensor feedback to determine fuel mix above 1500 RPM. I have also noticed at intermitent times that it will stay in the fault in the feedback system status till engine reaches 198* degrees and above. [ History ] New upstream O2 sensor, Will this status effect fuel econemy or is it normal for a 1997 volvo 850 O2 sensor to operate like this?

Post by **Ozark Lee** » 25 Apr 2019, 19:59

Mine always go closed loop fairly quickly, even on a cold day a city block or 2 will do it.

Anytime you are open loop the fuel mileage will suffer.

What kind of sensor did you use?

...Lee

Resistolcowboy · Post by **Resistolcowboy** » 27 Apr 2019, 10:56

I installed a Bosch O2 sensor from IPD. A automotive technician from the college I work at says the O2 sensor is not sending feedback to ECM, but the fault in the feedback system happens at 1500 rpm and lower only. I'm gonna inspect the wires at the connecting harness before the Sensor. Other than the fault my 850 gets 19.5 to 20 MPG City and 26 to 29 MPG Highway.

Post by **abscate** » 01 May 2019, 04:06

This could be a case of the diagnostic tool not reporting correctly.