Help, my 2007 4Runner V8 just threw a P0172 code and there doesn't seem to be much info associated with this code on the forum for 4th gens. Does anyone have any ideas where to start? I'm going to try cleaning the MAF and see what happens... other ideas? The 02 sensor is $164, which seems a little pricey to just replace on a wim. Other thoughts? Thank you!
P0172 Bank 1 Running Rich
- Thread starter cice
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Some things to check:
Clean the MAF first, make sure you use MAF cleaner, not Carb cleaner
Engine coolant sensor
Airbox connection, if there is a leak and excess air is getting in to the MAF sensor
Clean Air filter
Best of luck, let us know how it goes.
Some things to check:
Clean the MAF first, make sure you use MAF cleaner, not Carb cleaner
Engine coolant sensor
Airbox connection, if there is a leak and excess air is getting in to the MAF sensor
Clean Air filter
Best of luck, let us know how it goes.
Well you were right, after two weeks it has come back on. Now it is throwing P0172 (bank 1 too rich) and P0175 (bank 2 too rich). Should I replace the MAF since cleaning it made the original P0172 code go away? Maybe replace the 02 sensors (are there one or two for the V8)?
If it is an injector (or multiple injectors) how do I test this? Thank you!
If it is an injector (or multiple injectors) how do I test this? Thank you!
One way would be to connect a fuel pressure gauge to the fuel system and pressurize it by turning the key on. Then turn the key off and watch the gauge. The pressure should hold fairly steady for a little while, (sorry I don't remember how long exactly). But if it bleeds off pressure in say 15-30 minutes, you likely have an injector leaking. You might also be able to tell by pulling the plugs and looking for any that are wet with gas or really black. Hope this helps some.
Good ideas, the spark plugs are a very good place to start. Thank you!
I cleaned the MAF and the CEL went away all on its own after a little driving. I've ordered a new Hitachi MAF, which I think is OEM as the MAF in my vehicle says Hitachi on it. I'm also going to replace the two upstream o2 sensors as well. Hopefully with these are the cause of the problem. If not, I'll be pulling the plugs and also doing the pressure test.
I cleaned the MAF and the CEL went away all on its own after a little driving. I've ordered a new Hitachi MAF, which I think is OEM as the MAF in my vehicle says Hitachi on it. I'm also going to replace the two upstream o2 sensors as well. Hopefully with these are the cause of the problem. If not, I'll be pulling the plugs and also doing the pressure test.
After about three weeks of driving the P0172 and P0175 codes came back. I wasn't brave enough to attempt the fuel pressure check, so I took it to a shop. They cleaned the throttle body and the codes went away. After checking the fuel pressure, driving it with their monitoring computer attached, they finally decided there is nothing else wrong. So for anyone still following or who finds this thread, try cleaning the throttle body also. Hopefully this is the end of the rich codes saga for my 4Runner.
