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Service Engine Soon Light On ???"s

Old 06-29-2012, 02:21 PM
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Service Engine Soon Light On ???"s

I have a 2001 Camaro Z28 with 91K miles on it the car has SLP Air Box,SLP MAF Sensor,K&N filter and SLP after cat exhaust system and the Service Engine Soon light came on and I took car to Advance Auto to see what codes light gave it, it came back as P0171 Bank 1 too lean and P0174 Bank 2 too lean does these codes mean the O2 Sensors or what and if so which banks are which?THANKS

Last edited by dickeymoore; 06-29-2012 at 02:49 PM.
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Old 06-30-2012, 03:56 PM
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Re: Service Engine Soon Light On ???"s

The codes are telling you that the engine would be running lean, if the PCM was not adding more than 20% extra fuel over the standard caculation. When the PCM has to add that much fuel, there's something definitely wrong.

It could be a "true" lean condition, caused by low fuel pressure, faulty MAF sensor readings, air bypassing the MAF sensor, a vacuum leak, etc.

Could be a "false" lean condition, caused by exhaust leaks before the O2 sensors, excessive misfires, or fault O2 sensors. If you have a false lean condition, and the PCM was adding 20% extra fuel, it would likely be running rough, and the exhaust would smell of fuel. It would also be odd for the O2 sensors in both banks to fail at the same time, or to have exhaust leaks or misfires on both banks.

Check the fuel pressure for starters. Check the air intake tract for leaks after the MAF sensor. Check the engine for a major vacuum leak.

Bank 1 is the driver's side of the engine, Bank 2 is the passenger side.
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Old 06-30-2012, 04:45 PM
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Re: Service Engine Soon Light On ???"s

Couple of questions here, did the light come on after or before any of the afore mentioned mods? Also, did you recently clean and re-oil the K&N? Just trying to cut down the chances of anything being changed that might have caused the ses light to come on.
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Old 07-02-2012, 06:40 PM
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Re: Service Engine Soon Light On ???"s

Sell the SLP MAF and put a stock MAF back on. Disconnect the battery for several minutes to clear the PCM. If the DTCs return, VERY THOROUGHLY inspect the PCV system for leaks.
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Old 07-11-2012, 11:25 AM
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Re: Service Engine Soon Light On ???"s

mine goes off every time my air filters dirty , i clean it & it takes 3 to 7 days to go out (by itself). also make sure you turn / twist your gas cap plenty. just my 1 cent. cheers
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