LS1 Based Engine Tech LS1 / LS6 / LS2 / LS3 / LS7 Engine Tech

Service Engine Soon Light On ???"s

Old 06-29-2012, 02:21 PM
Registered User
Thread Starter
Join Date: Mar 2009
Posts: 49
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.
dickeymoore is offline  
Old 06-30-2012, 03:56 PM
Super Moderator
Injuneer's Avatar
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 67,208
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.
Injuneer is offline  
Old 06-30-2012, 04:45 PM
Registered User
Join Date: Jun 2012
Location: Masschusetts
Posts: 21
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.
BigMac76 is offline  
Old 07-02-2012, 06:40 PM
Registered User
Join Date: Dec 1999
Location: MD
Posts: 2,022
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.
Marc 85Z28 is offline  
Old 07-11-2012, 11:25 AM
Registered User
Join Date: Dec 2003
Location: ST PAUL,MN
Posts: 122
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
DANOZ28 is offline  
Related Topics
Thread Starter
Last Post
General 1967-2002 F-Body Tech
01-14-2015 09:57 AM
General 1967-2002 F-Body Tech
01-09-2015 04:58 AM
LT1 Based Engine Tech
12-15-2014 09:36 AM
Parts For Sale
12-06-2014 08:45 AM
South Atlantic
11-28-2014 03:22 PM

Thread Tools
Search this Thread
Quick Reply: Service Engine Soon Light On ???"s

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.