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Discussion Starter · #1 ·
Hello,

I went for a 2 minute to drive to collect some diagnostic data and discovered my 'Short term fuel trim (Bank 1 Sensor 2) (%)' is constantly reading 99.21875%.

So it's reading super lean, but given the constant nature one might speculate that the sensor is bad.

I see that the O2 sensor is after the catalytic converter, but the O2 sensor seems to be reading OK.

Bank 1 sensor 2 is going to be the O2 sensor after the catalytic converter,
Where is this fuel trim sensor located?
Is it possible that an injector is stuck closed?

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Full data log: OBD Fusion CSV Log

Note: I was collecting this data to investigate a fuel pressure leak - I recently replaced my fuel pressure regulator which seems to have fixed my long cranking starts, but I still lose 10 PSI of fuel pressure key off within 10 minutes, eventually down to 40 PSI.
 

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05 Astro AWD
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The PCM determines the fuel trims using the oxygen sensors. There is no 'fuel trim sensor'.

Bank 1 Sensor 2 refers to the oxygen sensor after the cat.
 

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2005 Astro Cargo 4WD
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Were those numbers collected during open loop? The PCM doesn't control the fuel trims using the O2 sensors until it reaches closed loop. The numbers could be all over the place in open loop.
 

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Discussion Starter · #4 ·
I'm not sure. It was a short drive, so I suspect that it wasn't if it takes some time to go into closed loop. Trim is the same as Fuel System 1/2 status changes, but I don't know what these values mean. I will get some values on a highway drive soon.

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Were those numbers collected during open loop? The PCM doesn't control the fuel trims using the O2 sensors until it reaches closed loop. The numbers could be all over the place in open loop.
Whoops, totally didn't consider short drive/open loop.

Also, the back O2 sensor really is just checking that the catalyst is performing as it's expected to. The front sensors do the most work. I did have one start to go bad, but it was factory, had a lot miles and a lot of raw gas from the screwed-up ignition system and leaking injectors.
 
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