SC400 PO171 code driving me nuts

When the cel P0171 came on I took it to the shop, they cleaned the MAF sensos they cleared the codes drove it and the CEL came back on with P0171
code then they replaced the MAF cleaded the codes drove it CEL back on. The car runs great no problems. Shop says its probably not the o2 sensor. Any one have any idea's on what keeps causing the CEL to come on with P0171 code?? HELP!
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O2 sensors are the first place to start. (after basic checks of is everything bolted on and not leaking. I would also check fuel pressure. I assume you have good fuel in it? And the fuel cap done up properly.
mrcheerful
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No leaking of anything they also cleaned the injectors the MAf and then replaced the MAF. the odbII does not indicate an o2. I will have them check the fuel pressure and possibly change the filter. Any other thoughts? Thanks for your help
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Check with mechanic they checked the fuel pressure no problem found, changed filter still gives error po171. The first code was po130 O2 that was cleared and never came back.
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Lexussc400 wrote:

Hope you aren't using a K&N air filter - they can contaminate the MAF sensor.
Is the MAF sensor a Bosch? They had a bad problem with OEM replacements in late 2004. http://www.vcertt.org/news/8-04.pdf
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I purchased the MAF from lexus
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Lexussc400 wrote:

Could still be a Bosch sensor, and it could be bad. Just guessing from here, however.
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I purchased the MAF from lexus
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Areas to look at for this code; Fuel Line pressure Injector Blockage O2 sensor MAF Engine Coolant Temp Sensor
-d

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What year sc?

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This is a difficult code to troubleshoot after the first or second guess at fixing it.
If the mechanic is willing to keep working on it and not charging you then let them keep working on it. If not, you can buy your husband one of those cheap $200 Code Readers. He then can work on it until he is blue in the face then he will tell you to take it back to the dealer.
If all else fails and you see a repeating pattern that espcially Lexus Codes mean a magnitude of problems you could always buy something like a Geo Metro.
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This is a difficult code to troubleshoot after the first or second guess at fixing it.
If the mechanic is willing to keep working on it and not charging you then let them keep working on it. If not, you can buy your husband one of those cheap $200 Code Readers. He then can work on it until he is blue in the face then he will tell you to take it back to the dealer.
If all else fails and you see a repeating pattern that espcially Lexus Codes mean a magnitude of problems you could always buy something like a Geo Metro.
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