Issues after O2 sensors replaced


New Member
I have a 2002 Chevy Silverado 1500 with a 5.3, we had a code showing bad O2 sensor and MAF so we cleaned the MAF and changed out all 4 O2 sensors. I took the truck to work and it was using fuel like I was pouring it out, and idling way low and really rough. When I checked the oil it was high and smelled like gas the check engine light did not come back on for a few days but when it did it showed 4 new codes...PO171 too lean bank 1...PO174 too lean bank 2 and P1133 fuel air metering ..P1153 fuel air metering. I have never really had issues with the truck until I "fixed" it. Any suggestions I would appreciate. Oh and I did go ahead and put a new MAF on and it did not fix the problem.


Gold Supporter
It sounds like your O2 sensors are not working correctly. The P1133 and P1153 are "insufficient switching" for the O2 sensors. It sounds like they're stuck lean. Are you sure that you have the correct ones and put them in the correct place? I would also check to be sure that none of the wires going to the sensors have damage.

The O2 sensors before the CAT should switch voltage back and forth from low to high. If you have a scan tool you can watch and see what is going on.


Your O2 sensors are off somehow. Did you reset your PCM after doing all of that work? Sometimes it benefits you and the PCM to do a reset and let it relearn the truck from a clean slate.


Gold Supporter
I had a whole slew of codes when I had an intake leak... Check the sensors first then go from there.


If you used Bosch sensors, bad idea. I know that's all that the parts stores usually carry but GMs don't usually like them. AC Delco or Denso (OEM for AC Delco sensors) only, in my experience.


Do you have the part numbers for the sensors you installed? What brand?
I already had to move it from the 360 forum for more accurate responses...


I already had to move it from the 360 forum for more accurate responses...
I had also incorrectly moved it to the 360 5.3 section but moved it back here.

Hope we find out something about this.


Lifetime VIP Supporter
When time permits... Please list your Mileage and consider changing the Fuel Contaminated Motor Oil and Oil Filter over to Mobil1 5W-30 (or better yet for Cold Weather ...Mobil1 0W-30) and a New Mobil1 or K&N Oil Filter as soon as you can as the lubricity will have been effectively 'watered down' enough to cause excessive engine wear. Depending upon how long you've had to run the Truck under the present problem conditions... excess amounts of unburned Gasoline can also ruin your Catalytic Converter.

The fact that so much Gasoline has migrated into the Oil Pan enough to actually raise the Oil Volume and Level strongly indicates the engine may be suffering from having the Low "Squeeze"-Pressure Top and Second Compression Rings becoming "Carbon Welded" deep inside of the Ring Grooves and cover the Piston Heads and Upper Cylinder Head and Valve Seats which have probably become quite choked up with Carbon Deposits over time.

If present... the artifacts of having Stuck Rings invite very excessive Blow-By and Low Compression problems...hence the presence of a lot of Unburned Fuel 'sneaking' around the Pistons. There are quite a few GMTN Threads that cover treating the Combustion Chambers and Rings of the Vortec I-6 and in this case, the 5.3L V8 Engines using the ACDelco TEC (Foaming Top Engine Cleaner) to very effectively remove any excess Carbon Deposits and improve your Compression and Fuel Economy. The ACDelco TEC is available here... in the Can as a Pure Liquid and also as a Foam Spray which may be easier to use on a V8 Engine. Having Two Cans of this stuff will guarantee achieving a thorough dosing for both V8 Engine Cylinder Banks:



New Member
Update: Thank you all for your suggestion and help! So we rest the pcm still no luck, then we bought the AC Delco sensors and that is what the problem turned out to be, I had put in Bosch sensors. We changed the oil and filter ran it for 15 miles and changed it again. The idle is smooth and I am about where I was before I changed out the sensors on gas usage. So after 2 sets of sensors, a new MAF and 3 oil changes thanks to your help I have my truck back.

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