I’ve been tracking down what is causing a low fuel trim bank 1 code and extra vibration throughout the vehicle(steering wheel will vibrate the harshest). It’s not a choppy rough idle, but a steady yet harsh vibration. I’ve gone through the list of things that everyone was kind enough to suggest in my last post. I’m fairly sure I’ve figured out the culprit, but there is yet another issue. When I came to the o2 sensors, the mechanic I had helping me said that the downstream sensor was reading just fine even if the sensor was not installed. Any ideas as to why it reads the sensor even if it’s not installed and even more importantly what to do to fix this? Computer reflash is just about all I can think of due to it being a transplant motor from a Colorado 07 3.7l. Any suggestions or help is appreciated!

 

P0171:Fuel Trim System Lean

Cause:

• The long term FT weighted average value is more or less than a calibrated value.
• The above condition is present for approximately 3 minutes after the conditions for running the DTC have been met.

Check wiring+clean/seal connectors to the MAF & MAP.

 

maybe the o2 sensors plugs are swapped? disconnect the other ones one bye one and see if it stops reading