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Trouble codes



Hi-i wanted to see if i could pic a techs brain on some codes that have been popping up please.

2009 Silverado 5.3 w/ flex fuel

P0175-"system too rich". I checked the MIT and air box and all seems tight, i bench tested both up stream O2 sensors and they were ok. Then i cleaned the MAF sensor and the check engine light went off for five days with typical driving.

Yesterday i got a P2270-"O2 sensor signal biased/stuck lean". The scanner said to replace bank 1 sensor 2. Does this sound right? I plan to bench test the down stream sensors tonight. Also no check engine light this morning.


Just wanted to check here, i need to order the sensor if needed.

Thank you for any help!



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P2270 2009 CHEVROLET SILVERADO 1500 LT V8 5.3

HO2S Signal Stuck Lean Bank 1 Sensor 2

The ECM detected the HO2S12 sensor has reported a lean condition for an extended period during an intrusive test

Probable Cause

1. Air leak near HO2S2
2. Failed HO2S2

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A scan tool does not tell you to replace anything! It only identifies a problem with a said system.

Flex fuel? Use a GM tech 2 and check the fuel alcohol content. For straight gas, it should be no higher than approx 15%.

If more than that, relearn procedure may be in order.

ALWAYS SHUT ENGINE OFF AND TURN KEY OFF FOR REFUELING! Failure to do this will skew the vehicle alcohol learn procedure. Inturn sets false rich/lean codes.

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Man....can't believe its been 2 months!

I switched the sensors as suggested and I didn't throw a code until just the other day. It finally warmed up to the 50's and check engine light came on. I got it scanned and the trouble code followed the sensor to the passenger side. Installing a new sensor tonight.


I wanted to update my findings and give a huge THANK YOU to Duelin! Merry Christmas, Josh


Sent from my Nexus 7 using Tapatalk



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Switch the right sensor with the left one and see if the code follows the sensor. Also check the pins and contacts on both the harness and o2 sensor connectors for any corrosion that might affect the values that are being sent to the computer. Also look at the harness real close to see if there is any damage.

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