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Discussion Starter #1
Hi all, I have been up against it chasing a bank 2 gremlin. Started with a Bank 2 Sensor 1 P0051 code (O2 heater circuit), replaced with Denso 234-9042. Now I’ve got a recurring P0174 (bank 2 lean) and P2197 (stuck lean). Short term fuel trims were plus 20 and up percent for bank two, two separate vacuum leak repairs had fuel trims on both banks to plus/minus single digits. Sounded better, ran better.... had my new BlueDriver plugged in to watch live data and literally watched trims go from single digits to minus 20 to plus 20 (with a long term of plus 53% when it logged the freeze grams data when the two codes returned.
This is the short version, I’ve had the firmware updated by the dealer and went back to the Denso sensor after the superceded OE part number for the B2S1 threw an immediate P2241 (sensor circuit voltage fault), which the Denso does not trigger.
I read there is no fuel pressure service port, but with no more apparent vacuum leaks and proper (usually close to 3.3v for both) B1S1 and B2S2 voltages, could it be likely that I’ve got a fuel delivery problem for bank two? I do notice with live data that B2 at times goes into CL-fault. Thanks everyone for any and all assistance. It’s a 2004 with 155K.
 

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I am curious to find out too. I have a code P074 for lean condition Bank 2. The pre cat AF sensors for both banks show voltage range from 3.02 -3.4v for Bank1 and 3.15-3.48v for bank 2. These values at approx 2500 rpm
In addition there is a P0420 for the catalytic Converter below threshold for Bank 1.
 

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I changed the hose that leads from the intake resonator to the valve cover as it had a crack, the pcv hose ( hard and very brittle) and both post catalytic oxygen sensors. My fuel trims are much better now and the codes P0174 and P0420 have not come back.
 

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Discussion Starter #4
Hey Paul, I didn’t follow up to your comment because I’m still chasing. Feels like a misfire at highway speed, but not severe - just a faint shudder (whether or not my trims are good and irregardless of codes or no codes).
I have not had any misfire or cat codes, just the P0174 and P2197.
A new fuel damper is on order, hopefully will swap it out early next week.
Good news on your issue!
 

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Discussion Starter #5
Update....looks like the last part I looked at is the same as the first. I think I either had a defective or returned/boxed wrong Denso sensor. Watching both upstream sensors on live data, the replaced Denso was actually sticking at 5.00 volts with highway RPM decel/fuel “cuts”.

Put in a OE non-superceded (89467-08010) sensor, have gone a hundred and ten miles with live data showing both sensor behaving exactly the same and no codes.
 

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Awesome, thanks for the update. The upstreams on mine fluctuate 3.2v-3.5 ish during cruise (2000 rpms) which I believe is indicative of a stoichiometric condition (ideal). I find it amazing that just changing out both of the sensor 2s ( post cat/downstream) gives better fuel trims. I find that the average fuel that shows on the overhead panel is more realistic. In town average 16-17mpg and highways 23-25 mpg.
Recently on one of my other cars I got a p0300 code for random misfire. Changing out all 6 plugs. original, platinum? 85k miles , 11 years and coil packs( preventative ) and both upstream oxygen sensors took care of the code. Bank 2 sensor 1 was toast and so were three of the coil packs . All plugs had wide gaps and those in bank 2 were all sooty.
This is the years for 02 sensors for me.
 
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