Fuel Trim

Hi, 2016 FORD Fiesta 1.6ltr Duratec 16v Ti-VCT engine. Main problem was a warped cylinder head due several overheating for not having sufficiant engine coolant in coolant system. Cylinder head packing has been replaced and the cylinder head has been flattened at a machine shop. System runs fine no particular issue at all, I was about to deliver it to the customer when the check engine light pop on suddenly. Scan tool shows a P2195 DTC. When I wanted to check the live scan data for the upstream O2 along with the trim data I noticed that the short trim data is stuck at 0% while the long trim is at about -12%.Upstream O2 is also stuck at 1.1 mAmps. With no response at higher rpms. Only amps data is available for this sensor, its a 6 wire sensor. The down stream sensor is cycling normal and reacting with rpm change. I am not familiar with this kind of 6wire sensors, I am not sure how to interpret the mamps data in the air/fuel mixture control. Any suggestions and/or comments are more than welcome as always, I don't have a valid way to bench test the O2 sensor to verify its condition. Not sure why I am not getting any short trim data (0%). Pls advice. Thank you all

What happens when you force a lean condition with a vacuum leak ?
Also how dose it respond and recover from a throttle isnap .
It is possible the sensor has been goosed by exposure to antifreeze but you are right to investigate first.

Hi, there is no reaction at all with a lean condition nor a throttle snap. it just keeps bouncing between 1.5 and 1.7 milli amps.

Is it going into closed loop? Try unplugging the sensor and see what it does. Also, if you are in generic OBDII data, try the OEM side (and vise versa) to see if there is something reporting besides mA.

I think 6 wire sensors have a pair of wires for a heater, fan, and sensor

It's a six wire sensor on the harness side, but only five going to the sensor. Of those five, only three are involved with the code you're getting. The other two are for the heater circuit.

If the code will not clear, and doing a KAM reset doesn't change anything, then you're pretty much down to a failed sensor. A reading of 1.1mA at all times indicates a stuck lean sensor, and the PCM knows it. :lol: So it's probably forced some kind of open loop condition to deal with the fault.

Did the code set while you were in fuel cut decel? Because that's usually when I see these sensors sticking lean. Usually they recover, sometimes they don't. :silly: This failure may be a product of the engine overheating.

I can walk you through the wiring checks, if you want. The details are dependent on if this Fiesta uses a Bosch sensor or an NTK sensor.

Thanks Tyler, I am pretty convinced that I am dealing with a faulty sensor. When ever I clear the code, It will come back after just idling for a while. Or if I use the scan tool and select the KOER self test for code reading, it will give you the code after the self test. I have ordered a new sensor and will be replacing it soon and will let you guys know what's the outcome. Thanks following this case!

Hello, thanks for your reply, it gives only mamps data In both OEM and Generic OBD mode.

Let us know how it goes!

rudolph.palm wrote: Hello, thanks for your reply, it gives only mamps data In both OEM and Generic OBD mode.

That's typical of Ford air/fuel ratio sensors. There's no converted 'voltage' PID like on Nissan and Toyota.