California smog i/m 02 sensor code needs complete

[MrTahoe92]

Howdy ya'll,
here in california got myself a 2003 chevy tahoe, I love her, only down side is, I've been struggling to get the 02 sensor i/m readiness to be ready for smog, No codes, she rides smooth, drove 100 miles now, since a month ago, did drive cycles, reset the monitors twice, all i/m readiness show good to go except the oxygen sensor.
Has 240k miles, got a new head gasket installed.

If anyone got any solutions let me know please, thank you! *tips cowboy hat in appreciation*

 

[Doubeleive]

Howdy ya'll,
here in california got myself a 2003 chevy tahoe, I love her, only down side is, I've been struggling to get the 02 sensor i/m readiness to be ready for smog, No codes, she rides smooth, drove 100 miles now, since a month ago, did drive cycles, reset the monitors twice, all i/m readiness show good to go except the oxygen sensor.
Has 240k miles, got a new head gasket installed.

If anyone got any solutions let me know please, thank you! *tips cowboy hat in appreciation*

Reseting just make it all start over again
you can pass smog in california with 1 monitor in "not ready" status in case you were not aware.

 

[MrTahoe92]

Howdy, partner only the evap one is permitted here in california to be not ready, I need the 02 sensor complete, only one left.

 

[TJ Baker]

Howdy ya'll,
here in california got myself a 2003 chevy tahoe, I love her, only down side is, I've been struggling to get the 02 sensor i/m readiness to be ready for smog, No codes, she rides smooth, drove 100 miles now, since a month ago, did drive cycles, reset the monitors twice, all i/m readiness show good to go except the oxygen sensor.
Has 240k miles, got a new head gasket installed.

If anyone got any solutions let me know please, thank you! *tips cowboy hat in appreciation*

Have you been able to see what DTC(s) have not run as required for the O2 I/M readiness to update to YES?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please. If we can't see it, it does not exist.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[MrTahoe92]

Have you been able to see what DTC(s) have not run as required for the O2 I/M readiness to update to YES?

Not sure if I understand my friend, I am no mechanic, can you explain in lame mans terms

 

[MrTahoe92]

Reseting just make it all start over again
you can pass smog in california with 1 monitor in "not ready" status in case you were not aware.

Can you be more specific in your resetting response friend? Like just disconnect battery or reset on ob2 scanner?

 

[MrTahoe92]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please. If we can't see it, it does not exist.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Howdy partner, thank you, I will post pictures after work asap, yeehaw!

 

[nonickatall]

Your o2 sensor works on the following principle: Your engine measures temperature, air volume, accelerator pedal position, and so on, and injects the necessary amount of fuel accordingly. Ideally, this mixture shouldn't burn too lean, which would produce nitrogen oxides, or too rich, which would produce soot and bad co measurements.

The oxygen content in the exhaust gas is also monitored. The o2 sensor reports this to the engine control unit (ECU), which then adjusts its injection quantity accordingly.

If you're not meeting the required emissions standards, this control loop isn't working correctly. This can have various causes. The lambda sensor could be old and defective; lambda sensors are wear parts.

Or the preceding control loop might have a problem, for example, a leak between the mass airflow sensor and the cylinder. This would result in an incorrect air volume reading, preventing the engine control unit from achieving a proper air-fuel mixture, which in turn would never produce a meaningful reading at the o2 sensor.

With problems like these, I would always first check the o2 sensors and read their values. They should have a reading of around 1. If one is completely outside the measurement range, it's obviously defective. If both readings are incorrect, the problem likely lies within the control loop. Furthermore, excessive air isn't the only culprit; old spark plugs, a faulty fuel pressure regulator, an incorrect temperature reading, and so on can also be contributing factors. Therefore, the most sensible approach is to connect a scanner and examine the live data. Someone who can interpret this data can quickly identify if any sensors are delivering incorrect readings. ,

Additionally a smoke test can be performed to determine if the intake air system is airtight.

If your smoke readings are still bad, it can also be a defective cat...

 

[TJ Baker]

Not sure if I understand my friend, I am no mechanic, can you explain in lame mans terms

I cannot accurately describe it cause I don't fully grasp it myself!!

For the O2 system I/M readiness monitor to update to YES it is more than one test. There are a handfull of diagnostics that must successfully run and pass. Some of these diagnostics run continuously when the proper conditions are met, and some only run once per ignition/drive cycle when the conditions are met.

This table linked below details what diagnostics are required for the I/M readiness monitor to update to YES.

There are two entries in the table for the O2 system under the system heading. These diagnostics must pass before the readiness monitor will update to YES.

Inspection/Maitenance (I/M) System (DTC) Table — 2003 Chevrolet C Tahoe 2WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2003 Chevrolet C Tahoe 2WD V8-5.3L VIN T.

charm.li

So,,, what good is this? If you knew which diagnostics were not successfully running it can help to pinpoint where the trouble may be.

So how do you know which diagnostics are not successfully running and completing??

Some scantools can display details of diagnostics (codes) telling if they have or have not run since the last time they were cleared. The scantool may also tell if the diagnostic (code) has passed, failed, or both.

So if one has such a scantool it may be possible to learn what diagnostic(s) are holding up the show and this can help in resolving the issue.

For the serious geek/nerd/whathaveyou... this can be done without the $$$ scantool but that is not a simple straightforward matter. It involves doing the communications hands on with the ECM/PCM and interpreting the responses yourself. Not for the average DIY guy or even the experienced mechanics.

Here's some more reading from the published service manual...

https://charm.li/Chevrolet/2003/C%20Tahoe%202WD%20V8-5.3L%20VIN%20T/Repair%20and%20Diagnosis/#Powertrain%20Management/Computers%20and%20Control%20Systems/Testing%20and%20Inspection/Monitors%2C%20Trips%2C%20Drive%20Cycles%20and%20Readiness%20Codes/I%2FM%20HO2S%2FO2S%20System%20Set/

 

[RET423]

Your 03 has 4 02 sensors, all 4 are heated

The 2 02 sensors located upstream of the catalytic converters assist the PCM in regulating the Air/Fuel ratio.

The 2 02 sensors located after the catalytic converters are used by the PCM to compare the content of the exhaust after the catalytic converter to the content before the catalytic converter that the upstream sensor is reporting; this enables the PCM to verify that your catalytic converters are still functioning

For your readiness monitors to set, the PCM determines that the heater circuit is working, the voltages reported to the PCM are within the diagnostic range & the rate at which those signals are being sent is rapid enough for the PCM to use in tuning

The downstream 02 sensors also can throw an additional code for low catalytic converter efficiency since that is what their purpose is but that usually won't delay an 02 Sensor readiness monitor pass or fail test

Your problem is odd because the checks the PCM does to verify proper 02 Sensor function are pretty simple, a cold start verifies the heater circuut, a short drive verifies the range of signal, a couple full lifts off the throttle to slow down verifies the signal speed

That usually means you get a green readiness monitor or a code telling you which of the 4 02 sensors failed the test & which function of that sensor didn't pass

100 miles of driving is plenty to either pass or set a code unless you keep clearing it manually which starts the whole process over again.

The only 02 sensor test that takes a bit of time is the catalyst efficiency test, if your trying those extenders on the rear 02 Sensors to trick the PCM into thinking the Catalytic Converters are working that can delay that test for a longer time & usually will end up failing the test & throwing the code anyway.

A decent scanner can tell you which test on which sensor is holding up the readiness monitor, if you don't have a scanner with that function you just have to be patient & keep driving until it sets or throws the code that will narrow it down

Good luck!

 

[nonickatall]

Your 03 has 4 02 sensors, all 4 are heated

The 2 02 sensors located upstream of the catalytic converters assist the PCM in regulating the Air/Fuel ratio.

The 2 02 sensors located after the catalytic converters are used by the PCM to compare the content of the exhaust after the catalytic converter to the content before the catalytic converter that the upstream sensor is reporting; this enables the PCM to verify that your catalytic converters are still functioning

For your readiness monitors to set, the PCM determines that the heater circuit is working, the voltages reported to the PCM are within the diagnostic range & the rate at which those signals are being sent is rapid enough for the PCM to use in tuning

The downstream 02 sensors also can throw an additional code for low catalytic converter efficiency since that is what their purpose is but that usually won't delay an 02 Sensor readiness monitor pass or fail test

Your problem is odd because the checks the PCM does to verify proper 02 Sensor function are pretty simple, a cold start verifies the heater circuut, a short drive verifies the range of signal, a couple full lifts off the throttle to slow down verifies the signal speed

That usually means you get a green readiness monitor or a code telling you which of the 4 02 sensors failed the test & which function of that sensor didn't pass

100 miles of driving is plenty to either pass or set a code unless you keep clearing it manually which starts the whole process over again.

The only 02 sensor test that takes a bit of time is the catalyst efficiency test, if your trying those extenders on the rear 02 Sensors to trick the PCM into thinking the Catalytic Converters are working that can delay that test for a longer time & usually will end up failing the test & throwing the code anyway.

A decent scanner can tell you which test on which sensor is holding up the readiness monitor, if you don't have a scanner with that function you just have to be patient & keep driving until it sets or throws the code that will narrow it down

Good luck!

Very good description.

You can also measure the o2 Sensor with a normal multimeter. Heating (two white cable) between 3-15Ω

The sensor wire (black to body ground), can be measured with a needle tip. It should read approximately 0.45 volts, or fluctuate between 0.1 and 0.9 volts. A multimeter typically only provides an average reading because it's too slow to measure. An oscilloscope offers a more accurate reading, but a multimeter is sufficient for a rough check of the sensor's functionality.

While measuring the sensor, engine must be in operation temperature.