ericksob

2003 Silverado V8 5.3L

I'mlooking for suggestions to eliminate my engine light from coming on. Signs are pointing toward the O2 Sensors, but I would like to confirm that before I putmoney into it. I have recently replaced the air filter and cleaned the Mass Air Flow Sensor as I learned those can sometimes lead to such engine codes. I've used a engine tech tool to gain the following data:

P0171 Bank 1 Fuel Trim System Lean
P0131 O2 Circuit LowVoltage Bank 1 Sensor 1
P1133 HO2/O2S Insufficient Switch Sensor 1 or Bank 1 Sensor

Additional "Freeze Frame" data at time of engine code trap:
FuelSystem 1: Closed Loop
Fuel System 2: ClosedLoop
Calculated Load: 1.9%
Temp:192 degrees F
STFT Bank 1: 51.5%
LTFT Bank 1: 25.0%
STFT Bank 2: 0.0%
LTFT Bank 2: 5.4%
Intake ManifoldPressure: 10.9 in*hg
RPM: 558
Speed: 0 MPH
MAF Sensor: 0.72 lb/min
Throttle Position: 4.3%


Thanks!

golfer

Kinda looking like the bank 1 sensor may need replacement but also check for leaks before the sensor.

ericksob

Thanks...any idea of expected manifold pressures, orexpected STFT and LTFT values. I believe they stand for Short Term Fuel Trim and Long Term Fuel Trim, buthave no clue what they should be. That goeswith mostof the data fromthe "Freeze Frame" featurefrom the diagnostic tool I used (Innova 3120 CanOBD 2 in 1Tool).

Does anyone know of a guide that details expected values for those outputs? The tool manufacturer doesn't seem to have any such thing.

jiggsy

Got these from an official GM Service Manual. Hope it gives you somewhere to start ...

PO171[/b]
Conditions for Setting the DTC

The average long term fuel trim cell value is above 23percent.
All of the above conditions are present for 6seconds.
200-800mV[/ul]

PO131[/b]
Conditions for Setting the DTC
Lean Test:
The PCM detects that the affected HO2S voltage parameter is
Less than 200mV for 165seconds.

Or

Power Enrichment Test:
The PCM detects that the affected HO2S voltage parameter is
less than 400mV for 10seconds.
[/b]
P1133[/b]
Conditions for Setting the DTC
The PCM detects that the affected HO2S lean-to-rich or rich-to-lean
transitions are less than a calibrated value.
250-625mV

ericksob

Has anyone ever swapped out O2 sensors before? Are they difficult to access (from what I've seen they appear to be).
How about the need for any thread locking material?
Are they fragile...any thing to look for or be careful of?

Thanks!

golfer

Depends which ones ... if you have ones located near the maniflods by the fire wall then those are ackward.


No ... actuallty you might want to use anti-sieze compound on the threads and only the threads don't get any on the sensing end.


Yes ... don't drop them or bang the sensing ends.