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Recently got a CEL+VSC+TRAC OFF light in our 2008 IS250. Codes come back as P0171/PO174 System too lean bank 1/2. Checked for vacuum leaks and we're all good. Haven't cleaned the MAF yet but ordered a new gas cap today because it feels like the current one doesn't seal and "click" fully. Since I just swapped out the fuel pump for used one on Friday, I'm wondering if it could be related to that? Any thoughts are appreciated. Thanks!
Recently got a CEL+VSC+TRAC OFF light in our 2008 IS250. Codes come back as P0171/PO174 System too lean bank 1/2. Checked for vacuum leaks and we're all good. Haven't cleaned the MAF yet but ordered a new gas cap today because it feels like the current one doesn't seal and "click" fully. Since I just swapped out the fuel pump for used one on Friday, I'm wondering if it could be related to that? Any thoughts are appreciated. Thanks!
You said you bought a complete module from eBay? How many miles on the unit? Clogged fuel filter? Maybe the fuel pump is too weak. I don't think the gas cap would cause a lean condition.
Hey Mike, I know it came out of a 2008 IS350 not sure on the mileage. She drove fine for a day and a half after changing the pump....as soon as I added the Seafoam (to about 1/2 tank of gas) that's when the problem occurred. When I googled "Seafoam P0171 P0174" it seems I'm not the only one with the problem. Do you think Seafoam would have caused the CEL to trigger? I can't think of anything else. Unless like you said the fuel filter on the used pump is clogged.
Hey Mike, I know it came out of a 2008 IS350 not sure on the mileage. She drove fine for a day and a half after changing the pump....as soon as I added the Seafoam (to about 1/2 tank of gas) that's when the problem occurred. When I googled "Seafoam P0171 P0174" it seems I'm not the only one with the problem. Do you think Seafoam would have caused the CEL to trigger? I can't think of anything else. Unless like you said the fuel filter on the used pump is clogged.
It's really hard to tell. Actually last tank I dumped 2 bottles of Chevron Fuel injector cleaner. No adverse effects here. Now I'm on a fresh tank I filled up last Thursday.
Ok, I will monitor it and keep you posted. The kid has it now as it drives great....no idle issues or anything. What I'll do is fill up one more time and let it run through and see if that improves things. If not, like you said time to look at the fuel filter on the (used) pump. Thanks again.
So the CEL came back and I finally got tired and dropped the car off at the dealer for diagnosis. The tech said he found a small gas leak from the cold start fuel line going into the intake, evidently the gasket was missing. I think when I put everything back together when I replaced the fuel pressure sensor it must have fallen out...I'm not even sure how that happened because I didn't detect any leak. Anyway, I'm just glad it's fixed!
Thanks Mike. Gville, remember this was not a Lexus flaw it was user error lol. I had Dad helping me and between the two of us we probably dropped the gasket...
11-18-18, 03:28 PM
P0171/P0174 Running lean
