Postby TooMuchControl » Mon Aug 07, 2023 9:11 pm
I'm nota master tech by any means, but I think my points below are correct,
A low voltage in S2 could simply mean an extended lean condition, with a failing A/F sensor, too.
You would see this in trim data where the LTFT would have long negatives, while your A/F sensor is stating it's in stoich balance.
You can wake up a S2 sensor by injecting gas into the intake ahead of the MAF to make sure.
A "good reading" from an A/F ratio sensor could mean it's in balance "with itself" but could be reading inaccurately. It's an easy check to verify A/F resistances at room temperature. Pins 3 and 4 should read somewhere close between 2.9-4 ohms I believe.
All other pin outs should show no continuity (1,2,5,6 to 3) and (1,2,5,6 to 4) - they should be open on the DVM.
Main question is: what quality are the parts in the truck?
Are the A/F sensors something close to OEM (Bosch, Denso, etc).
The MAF sensor. Is it aftermarket or is it a Nissan OEM part? I'm wondering in the chase of an issue, a non OEM part has been installed.
OEM may matter in a diagnosis. An inaccurate or a dirty MAF should be considered.
Nissan has a service procedure to detect a fuel delivery issue, by running the engine at a high rpm for 15 mins (2500-3000 rpm) after the MAF reset.
Unplugging the MAF sensor and resetting that code, should clear the trims and learned parameters, I believe.