Fuel Too Leak (Bank 2)

Tiny
JGONZO2398
  • MEMBER
  • 2008 HONDA ACCORD
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 178,000 MILES
So I’ve been stressing about this issue for over a week now. I had both valve cover gaskets replaced along with the plenum gasket, I also replaced my engine air filter. Later that same day when I drove my car, the CEL came on and I got that P0174 code for bank 2. I’ve been researching online and have cleaned the MAF sensor, checked for any loose or ripped hoses but everything seems solid. The RPMs at idle seem to be pretty normal but I’m nervous because I plan to take this car on a trip to California next week. The CEL with the same code has turned off on its own a couple times now then comes back on. Any guesses?
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Tuesday, November 4th, 2025 AT 10:21 AM

36 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,231 POSTS
As it has come on before for the same code then went away I might look at an injector flow test, one might be dirty or sticking, or it might be that bank one is running rich and the ECU thinks that means B2 is running lean. You might look at the fuel trims with a scan tool to see what they are doing, if it is adding fuel on B2 and B1 is normal then I would check for leakage, just spray around the plenum and manifold with starting fluid and see if anything changes. Check the EVAP purge as well, The hoses can come off and then you get a vacuum leak when it triggers the purge on.
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Tuesday, November 4th, 2025 AT 10:47 AM
Tiny
JGONZO2398
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I did a live data scan of the fuel trim with my FIXD scanner, didn’t even know I could do that, but here the average numbers. Not sure if that helps you at all
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Tuesday, November 4th, 2025 AT 11:44 AM
Tiny
STEVE W.
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They might except they don't show up. Do you see anything other than a logo on your end?
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Tuesday, November 4th, 2025 AT 12:26 PM
Tiny
JGONZO2398
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Short-Term Fuel Trim (STFT):
Bank 1 = 0 % to -1.6 %
Bank 2 = +16 % to +18 %

Long-Term Fuel Trim (LTFT):
Bank 1 = -0.8 % to 0 %
Bank 2 = +12.5 % to +13.3 %
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Tuesday, November 4th, 2025 AT 1:07 PM
Tiny
JGONZO2398
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And yes, I only see logos
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Tuesday, November 4th, 2025 AT 1:07 PM
Tiny
STEVE W.
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Thanks for the response on the images. Those numbers are showing it adding fuel. Try this watch them and then rev the engine up to 2500-3000 and hold it there for a bit. If the bank 2 starts to go down then you have a vacuum leak somewhere that is letting in air after the MAF
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Tuesday, November 4th, 2025 AT 1:48 PM
Tiny
JGONZO2398
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I actually already did that test, held the RPM at 2500 for 10-15 seconds, numbers looked very similar, STFT for Bank 2 stayed between +16% and +18%, LTFT was around +12% and +13%, Bank 1 remained around zero the whole time. Would this narrow it down to fuel injectors or purge valve? Maybe a gasket that didn’t properly seal or bolts that need to be torqued down more?
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Tuesday, November 4th, 2025 AT 2:11 PM
Tiny
STEVE W.
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OK if it stayed the same at higher rpm it probably isn't an air leak. What voltages are you able to see from the O2 sensor with the scan tool? Have you swapped the upstream sensor just to see if it has an issue?
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Tuesday, November 4th, 2025 AT 3:53 PM
Tiny
JGONZO2398
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Got it. So I actually did run a live data voltage test for the O2 sensors, the downstream O2 was hovering between 0.09V and 0.72V. My scanner couldn’t read Sensor 1 (it showed as “unsupported” in the scanner app). I haven’t swapped the upstream sensors yet, but I can check if they’re interchangeable to rule that out
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Tuesday, November 4th, 2025 AT 3:57 PM
Tiny
JGONZO2398
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My question is, would it be normal for it to be a sensor issue right after a gasket replacement job? Especially if I never had any issues with them to begin with and I didn’t disconnect them either in the job
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Tuesday, November 4th, 2025 AT 3:57 PM
Tiny
STEVE W.
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Would depend on what you might have hit by accident while working. There might be a wire that was hit or a bad connection and it was disturbed during the work. Or a piece of gasket might have gone through and blocked some of the sensor. Are you getting a single notification in your email or multiple updates?
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Tuesday, November 4th, 2025 AT 4:50 PM
Tiny
JGONZO2398
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A test I just tried now (as many users had mentioned online) was to spray carb cleaner along the intake manifold, throttle body and plenum and valve cover gasket areas, hoses surrounding the area as well but I didn’t see any spikes or changes in my RPMs
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Tuesday, November 4th, 2025 AT 5:08 PM
Tiny
STEVE W.
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Figured that would be the case. The earlier rev up while watching the trim indicated that there was no unmetered air like a vacuum leak. It is an easier test done from the drivers seat than doing the spray method. You don't have an exhaust leak on that side that might let air in near the sensor?
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Tuesday, November 4th, 2025 AT 7:07 PM
Tiny
JGONZO2398
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How could I check that? Do you think I should replace the O2 sensor on that front side of the engine?
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Tuesday, November 4th, 2025 AT 7:22 PM
Tiny
STEVE W.
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If you don't hear a leak it's likely not the problem, a leak at or lust after the converter can let in enough air that it will read lean and dump in fuel. As for the sensor, compare the voltages between both sides, Shut the engine off and look at the base voltage on a cold engine, they should be the same. Now start the engine and watch as they change, it should take a minute for it to go into closed loop, if the voltages are close then the sensor is probably OK and you have a different problem. That will take testing the rest of the fuel system, Fuel pressure and flow testing the injectors.
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Tuesday, November 4th, 2025 AT 10:26 PM
Tiny
JGONZO2398
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I’m not sure if I am up for all these tests if I’m being honest, I just ordered a new O2 sensor to replace that upstream sensor in bank 2, a new purge valve solenoid and a new PCV valve. Do you think it’s a good idea to replace all those?
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Tuesday, November 4th, 2025 AT 10:41 PM
Tiny
JGONZO2398
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I also ran some seafoam in my gas tank for the first time last week, this was after the valve cover gasket job
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Tuesday, November 4th, 2025 AT 10:41 PM
Tiny
STEVE W.
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Don't replace them all at once. Especially these days when it seems every third part is bad right out of the box. If you clear the codes, how long does it take for it to return? Did it get worse after the VC gaskets? If yes then look over the engine real close, pinched wire, loose connection, even a bad ground can change what the ECU "sees" from the sensors and cause problems.
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Wednesday, November 5th, 2025 AT 6:56 AM
Tiny
JGONZO2398
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I’d say it takes about two days or so for it to come back up, it’s definitely more than a day in between. This last time, it went away on its own which it’s done before. The time before that I turned it off and it stayed off for a couple days on the dash but it still comes up as a stored code when I scan it.
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Wednesday, November 5th, 2025 AT 7:09 AM
Tiny
JGONZO2398
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And it’s the same pattern of codes coming on and off since the valve cover gasket replacements, not better or worse
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Wednesday, November 5th, 2025 AT 7:09 AM

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