dcoperator

Does anyone know what may cause a SES code regarding bank 1 sensor 2 lean. Simple as replacing the sensor? Truck seems to run fine with 84000 on it. By the way it has the 5.3 w/fuel management.

EinST

I don't understand what you mean by "bank 1 sensor 2 lean." What exactly was the code? Post catalyst sensors do not determine a lean condition.

Chevrolet Customer Service

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I'm sorry to hear of your frustration with your Silverado. Replacing the sensor may resolve the problem; however, it depends on what the problem is. It may be a leak. These are just suggestions, it is not a diagnosis.

I encourage you to take the vehicle in for an inspection by a certified technician. A physical inspection will offer a more accurate diagnosis and repair option(s).

If you have additional questions, please feel free to contact me.

Louis
GM Customer Service

dcoperator

The code was P2270 which according to their printout " Heated oxygen sensor signal syuck lean sensor 2...
the ecm detected the HO2S Sensor 2 has reported a lean condition for an extended period during an intrusive test. Probable cause:
Air leak near HO2S2 (Sensor 2)
Failed HO2S2 ( Sensor 2 )

EinST

Hmm, that's one I've never come across. So, apparently this "intrusive test" intentionally adds fuel and then watches the post-catalyst O2 sensor to detect the rich condition. A defective sensor is a no-brainer but an exhaust gas leak near the sensor can lower the sensed voltage due to lower differential between the oxygen content in the exhaust and the outside air. That said, it kind of makes it hard to tamper with the system, doesn't it?

dcoperator

So would you suggest replacing the O2 sensor first?

MDTAHOE

As long as there is no exhaust leak the it almost has to be the sensor. There is a small possibility it could be something else. It would be the second sensor down on the drivers side behind the cat. Do not use a low budget sensor. Either get it from the dealer or someone who sells AcDelco parts. Here is the testing info from the factory manual, you can run the test if you have a DVOM.


TC P0133, P0134, P0140, P1133, P2270, P2271, P2A00, or P2A01

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection\Initial Inspection and Diagnostic Overview
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors

DTC P0133
HO2S Slow Response Bank 1 Sensor 1
DTC P0134
HO2S Circuit Insufficient Activity Bank 1 Sensor 1
DTC P0140
HO2S Circuit Insufficient Activity Bank 1 Sensor 2
DTC P1133
HO2S Insufficient Switching Bank 1 Sensor 1
DTC P2270
HO2S Signal Stuck Lean Bank 1 Sensor 2
DTC P2271
HO2S Signal Stuck Rich Bank 1 Sensor 2
DTC P2A01
HO2S Performance Bank 1 Sensor 2
Diagnostic Fault Information

Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The engine control module (ECM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started, the ECM operates in Open Loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream. Low HO2S voltage indicates a lean exhaust stream.

Conditions for Running the DTC

P0133
DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set.
The Engine Coolant Temperature (ECT) Sensor parameter is more than 60°C (140°F).
The Intake Air Temperature (IAT) Sensor parameter is more than -40°C (-40°F)
The Ignition 1 Signal parameter is between 10-18 volts.
The Fuel Level Sensor parameter is more than 10 percent.
The Engine Run Time parameter is more than 160 seconds.
The Engine Speed parameter is between 1,200-3,000 RPM.
The Barometric (BARO) Pressure parameter is more than 70 kPa.
The Mass Airflow (MAF) Sensor parameter is between 20-55 g/s.
The Loop Status parameter is Closed.
The Throttle Position (TP) Indicated Angle parameter is more than 5 percent.
DTC P0133 runs once per drive cycle when the above conditions are met for 1 second.
P0134
DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set.
The Ignition 1 Signal parameter is between 10-18 volts.
The engine run time is more than 300 seconds.
DTC P0134 runs continuously when the above conditions are met.
P0140
DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set.
The Ignition 1 Signal parameter is between 10-18 volts.
The Engine Run Time parameter is more than 300 seconds.
The Loop Status parameter is closed.
DTC P0140 runs once per drive cycle when the above conditions are met.
P1133
DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0442, P0443, P0446, P0449, P0455, P0496, P1516, P2101, P2119, P2135, P2176 are not set.
The ECT Sensor parameter is more than 60°C (140°F).
The Engine Speed parameter is between 1,200-3,000 RPM.
The Ignition 1 Signal parameter is between 10-18 volts.
The Engine Run Time parameter is more than 160 seconds.
The Loop Status parameter is Closed.
The TP Indicated Angle parameter is more than 5 percent.
The Fuel Level Sensor parameter is more than 10 percent.
The BARO Pressure parameter is more than 70 kPa.
The MAF Sensor parameter is between 20-55 g/s.
DTC P1133 runs once per drive cycle when the above conditions are met for 1 second.
P2270
DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.
The Ignition 1 Signal parameter is between 10-18 volts.
The Engine Run Time parameter is more than 5 minutes.
The Engine Speed parameter is between 1,100-2,500 RPM.
The MAF Sensor parameter is between 3-20 g/s.
The Vehicle Speed parameter is between 50-120 km/h (31-75 mph).
The Fuel Level Sensor parameter is more than 10 percent.
The Loop Status parameter is closed.
The Catalytic Converter Temperature parameter is between 550-900°C (1,022-1,652°F).
DTC P2270 runs once per drive cycle when the above conditions are met.
P2271
DTCs P0036, P0037, P0038, P0137, P0138, P0140, P0141, P0443, P0458, P0459, P2232 are not set.
The Ignition 1 Signal parameter is between 10-18 volts.
The Engine Speed parameter is between 500-5,000 RPM.
The MAF Sensor parameter is between 3-50 g/s.
The Vehicle Speed parameter is between 24-132 km/h (15-82 mph).
The Fuel Level Sensor parameter is more than 10 percent.
The Loop Status parameter is closed.
DTC P2271 runs once per drive cycle when the above conditions are met for 1 second.
P2A01
DTCs P0030, P0036, P0053, P0054, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0128, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0442, P0443, P0446, P0449, P0455, P0496, P1133, P1516, P2101, P2119, P2135, P2176, P2A00 are not set.
The Engine Run Time parameter is more than 5 minutes.
The Ignition 1 Signal parameter is between 10-18 volts.
The MAF sensor parameter is between 3-50 g/s.
The Engine Speed parameter is between 500-5,000 RPM.
The Vehicle Speed parameter is between 24-132 km/h (15-82 mph).
The Fuel Level Sensor parameter is more than 10 percent.
The Short Term FT parameter is between -4 and +4 percent.
DTC P2A01 runs once per drive cycle when the above conditions are met for 1 second.
Conditions for Setting the DTC

P0133
The ECM detects that the HO2S 1 rich-to-lean or lean-to-rich average response time is more than a calibrated value.
DTC P0133 sets within 100 seconds when the above condition is met.
P0134
The ECM detects that the HO2S 1 parameter is between 350-550 mV for 100 seconds.
The Throttle Position (TP) Indicated Angle parameter changes more than 5 percent, 1 time.
DTC P0134 sets within 100 seconds when the above conditions are met.
P0140
The ECM detects that the HO2S 1 parameter is between 410-490 mV.
The TP Indicated Angle parameter changes more than 5 percent 6 times.
DTC P0140 sets within 100 seconds when the above conditions are met.
P1133
The ECM detects that the HO2S 1 rich-to-lean counts, or the lean-to-rich counts are less than a calibrated value.
DTC P1133 sets within 100 seconds when the above condition is met.
P2270
The ECM detects that the HO2S 2 voltage oscillations are slower than a calibrated value.
DTC P2270 sets within 4 seconds when the above condition is met continuously, or within 50 seconds when the above condition is met cumulatively.
P2271
The ECM detects that the HO2S 2 voltage oscillations are faster than a calibrated value.
DTC P2271 sets within 4 seconds when the above condition is met continuously, or within 50 seconds when the above condition is met cumulatively.
P2A01
The ECM detects that the HO2S 1 did not transition below 200 mV and above 730 mV during the passive test.
One of the following tests fail:
Lean Intrusive Test
The ECM detects that the HO2S 1 is more than 200 mV for 12 seconds.
The sensor is less than 200 mV.
Rich Intrusive Test
The ECM detects that the HO2S 1 is less than 730 mV for 12 seconds.
The sensor is more than 730 mV.
DTC P2A01 sets within 5 minutes when the above conditions are met.
Action Taken When the DTC Sets

DTC P0133, P0134, P0140, P1134, P2270, P2271, P2A00, or P2A01 are Type B DTCs.

Conditions for Clearing the DTC

DTC P0133, P0134, P0140, P1134, P2270, P2271, P2A00, or P2A01 are Type B DTCs.

Circuit/System Verification

If any HO2S heater DTCs are set, perform those diagnostics first.
Allow the engine to reach operating temperature.
Engine running, observe the affected HO2S parameter with a scan tool.
The pre-catalyst oxygen sensors value should vary from below 200 mV to above 800 mV and respond to fueling changes.
The post-catalyst oxygen sensors value should change more than 200 mV when the throttle is quickly cycled 3 times from closed to wide open and back to closed after running the engine at 1,500 RPM for 30 seconds.
The affected HO2S may be damaged due to contamination. Prior to replacing the affected HO2S, inspect for the following sources of contamination:
Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice.

A silicon contaminated HO2S
Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool). See: Component Tests and General Diagnostics\Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) See: Component Tests and General Diagnostics\Alcohol/Contaminants-In-Fuel Diagnosis (With Special Tool)
Engine oil consumption-Refer to Oil Consumption Diagnosis. See: Engine, Cooling and Exhaust\Engine\Testing and Inspection\Component Tests and General Diagnostics
Engine coolant consumption-Refer to Loss of Coolant. See: Engine, Cooling and Exhaust\Cooling System\Testing and Inspection\Symptom Related Diagnostic Procedures\Loss of Coolant
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing

Important: All modules must be powered down or misdiagnosis may result.

Ignition OFF, disconnect the scan tool and wait 60 seconds to ensure all modules are powered down.
Ignition OFF, disconnect the harness connector at the appropriate HO2S.
Ignition OFF, measure for less than 5 ohms between the appropriate HO2S low signal circuit terminal A and ground.
If more than the specified range, test the appropriate HO2S low signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
Ignition ON, verify the appropriate scan tool HO2S parameter is approximately 450 mV.
If more than the specified value, test the appropriate HO2S high signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
If less than the specified value, test the appropriate HO2S high signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
Ignition ON, install a 3A fused jumper wire at the HO2S high signal circuit terminal B. Toggle the jumper wire between the HO2S low signal circuit terminal A and battery voltage. Verify the appropriate scan tool HO2S parameter toggles between 0 mV and approximately 1,000 mV.
If the appropriate scan tool HO2S parameter does not toggle correctly, test the HO2S high signal circuit for an open/high resistance. If the circuits test normal, replace the ECM.
If all circuits test normal, replace the appropriate HO2S.
Repair Instructions

Notice: Refer to Heated Oxygen Sensor Resistance Learn Reset Notice.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. See: Verification Tests and Procedures

Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (1500 Series) Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series) Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (2500 Series - Cab/Chassis)
Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series) Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series) Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series - Cab/Chassis)

dcoperator

Thanks for the input guys!