Help with a CEL, P0171
10-04-10, 01:38 PM
#16
According to some over @BITOG, Toyota/Lexus brand fluid tends to turn brown quickly. I have the same experience, and won't use it again.
You can do the tranny yourself if you want to save a lot of $$$. The ATF Type IV is only $3.49 at the dealer. There is a DIY at Lexls.com that you can use as a guide. You'll probably need about 12 quarts to completely flush it. I think dealer will charge about $150+ for that job.
Well, got my car smogged and it barely passed despite all that they did for it. My hydrocarbons were at 51 ppm @15 mph, max in Calif. is 51, all my other numbers were well below the max. I cant believe this. Why am I at max, one more point higher and I would of failed smog. I wonder if my cat. converter is about to fail? Any suggestions. Thanks.
10-04-10, 02:42 PM
#17
Could be some vacuum carbon deposits. Yep.. Thats living in Cali for yah hehehee... What year is you car again? Usually it will throw a CEL if your cat goes bad with OBD2's. OBD1 I don't think so and that cat might be it.... There has also been lots of instances where the cat is not hot/warm enough. People recommend that you keep the car warmed up before taking it for a smog check... I usually would drive around for 30mins or about 15+ miles then smog the car. I also usually don't turn the car off when I get to the smog station until they drive the car to the machine. I get a whole lot better result that way than driving the car from home immediately to the smog station and getting it smog right away with cold cats.
10-04-10, 04:32 PM
#18
Could be some vacuum carbon deposits. Yep.. Thats living in Cali for yah hehehee... What year is you car again? Usually it will throw a CEL if your cat goes bad with OBD2's. OBD1 I don't think so and that cat might be it.... There has also been lots of instances where the cat is not hot/warm enough. People recommend that you keep the car warmed up before taking it for a smog check... I usually would drive around for 30mins or about 15+ miles then smog the car. I also usually don't turn the car off when I get to the smog station until they drive the car to the machine. I get a whole lot better result that way than driving the car from home immediately to the smog station and getting it smog right away with cold cats.
10-14-10, 05:22 PM
#19
Update:
Well, I thought my CEL issue was resolved after taking it to the dealer. Well, the other weekend happened to be a hot weather weekend and the CEL came on. I've noticed if the outside temp. is greater than 90 degrees I get the CEL with the code of P0171 and when its cool, less then 70 degrees the CEL turns off. I took my car back to the dealer and the guy said its filter oil on my MAF sensor and the master tech. said I should put back my stock air filter, otherwise I will have problems with the CEL coming on and off. I told the dealer that when I took it to them the first time and picked up my car, I switched out my K&N filter with a dry foam filter and have been using it since. I dont understand how filter oil can be on there again. Anyways, I did my search on here and read that after getting filter oil on the MAF sensor and/or multiple cleanings can ruin the MAF sensor and when replaced with a new MAF sensor the issue is resolved. Well, I bought a new MAF Toyota Denso sensor off ebay yesterday, we'll see if it resolves the issue. Also, I showed the dealer my smog results and now they are saying my Cat. Convert. is on the verge of failing and some of the honeycombs inside have broken off. Time for a new Cat. Converter.
Well, I thought my CEL issue was resolved after taking it to the dealer. Well, the other weekend happened to be a hot weather weekend and the CEL came on. I've noticed if the outside temp. is greater than 90 degrees I get the CEL with the code of P0171 and when its cool, less then 70 degrees the CEL turns off. I took my car back to the dealer and the guy said its filter oil on my MAF sensor and the master tech. said I should put back my stock air filter, otherwise I will have problems with the CEL coming on and off. I told the dealer that when I took it to them the first time and picked up my car, I switched out my K&N filter with a dry foam filter and have been using it since. I dont understand how filter oil can be on there again. Anyways, I did my search on here and read that after getting filter oil on the MAF sensor and/or multiple cleanings can ruin the MAF sensor and when replaced with a new MAF sensor the issue is resolved. Well, I bought a new MAF Toyota Denso sensor off ebay yesterday, we'll see if it resolves the issue. Also, I showed the dealer my smog results and now they are saying my Cat. Convert. is on the verge of failing and some of the honeycombs inside have broken off. Time for a new Cat. Converter.
10-15-10, 05:00 PM
#20
let me know if you find a solution. I have the same problem and its been on and off for about 4 months now. It only happens when it's hot out. I live in Houston and its been pretty cool in the mornings so when I drive to work (50 mile drive) its no problem. But on the way home, the check engine light pops up right after 5 miles or so. I can clear it since I have a scanner but I'm still trying to hunt down the problem. I went to a shop and checked for vacuum leaks and they found none. Every time I pull the code, its a p0171 system too lean/bank 1 code.
Last edited by PlatES300; 10-15-10 at 05:08 PM.
10-15-10, 05:19 PM
#21
let me know if you find a solution. I have the same problem and its been on and off for about 4 months now. It only happens when it's hot out. I live in Houston and its been pretty cool in the mornings so when I drive to work (50 mile drive) its no problem. But on the way home, the check engine light pops up right after 5 miles or so. I can clear it since I have a scanner but I'm still trying to hunt down the problem. I went to a shop and checked for vacuum leaks and they found none. Every time I pull the code, its a p0171 system too lean/bank 1 code.
10-15-10, 05:28 PM
#22
Wow, thats the exact problem I'm having too, when it's above 90 degrees and im driving a while the CEL comes on, but when I'm driving in the evening when it's cooler, the CEL goes off, I have the same code as you. I did a search on here and found others had the same issue with the same code and it was linked to the MAF sensor, problem being the intake system, OP were using K&N filters which the oil would hit the MAF sensor and then throw the P0171 code. OP have said that our engines dont like the extra air from an aftermarket intake system, causes the same code. I've also read that multiple cleanings of the MAF sensor causes issues and the issue is resolved by replacing with a brand new Toyota Denso MAF sensor. Ultimately, it seems the MAF sensor over time wears out and by replacing with a new one resolves the issue. I took my car to the dealer and they say the MAF is causing the problem because of my aftermarket cold air intake, they said oil or debris from the cold air intake filters collect on the MAF and cause the code. Well, I bought a new MAF sensor, will replace over the weekend and I will update.
10-19-10, 04:59 PM
#23
Suppose to get the new MAF sensor tomorrow, the guy I ordered from via ebay accidently sent me the MAF for a 99 ES300, so he had to resend me the correct one. Interesting that your not running an aftermarket intake and your getting the same code. I then am leaning that the MAF sensor is the culprit, faulty MAF sensor causing the P0171. I recently received a P0330, knock sensor malfunction, bank 2 along with my P0171 code. I'm hoping the P0171 is causing the knock sensor code. My car runs fine and no misfires what so ever, cant figure out what would cause a P0330 code. I reset my ECU and seeing if I get the P0330 code again along with the P0171. Will keep you posted.
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