P2272 O2 Sensor Signal Stuck Lean B2S2
OBD-II Trouble Code Technical Description
O2 Sensor Signal Stuck Lean Bank 2 Sensor 2
What does that mean?
This is a generic powertrain code, which means it covers all makes/models, 1996-newer. However, specific troubleshooting steps will vary depending on the vehicle.
This P2272 trouble code refers to the post-catalytic converter O2 (oxygen) sensor on bank #1, sensor #2. This post-cat sensor is used for monitoring the efficiency of the catalytic converter. The converter’s job is to reduce emissions out the tailpipe. When the signal from the O2 sensor is detected by the PCM as being stuck lean or biased lean, this DTC is set.
The P2272 DTC refers to downstream sensor (after the catalytic converter), sensor #2 on bank #2. Bank #2 is the side of the engine that does not contain cylinder #1. There may be a third sensor downstream, if that is the problem, a P2276 is set.
This code is basically telling you that the signal put out by the particular oxygen sensor is stuck lean (meaning too much air in the exhaust).
Note: Some manufacturers such as Ford may refer to this as a Catalyst Monitor Sensor, same thing, different name. This DTC is very similar to P2197. If you have multiple DTC codes, fix them in the order they appear.
Symptoms
Most likely you will not notice any drivability issues since this is not sensor #1. You will notice Malfunction Indicator Lamp (MIL) illumination. In some cases however, the engine may run rough.
Potential Causes
The causes for this DTC may include:
Exhaust leak near O2 sensor Contaminated or failed HO2S2 (Sensor 2) HO2S2 wiring/circuit problem Loose installation of HO2S2 Fuel pressure incorrect Faulty fuel injector Engine coolant leak Faulty purge solenoid valve PCM has failedDiagnostic and Repair Procedures
Visually inspect the wiring and connectors for corrosion, rubbed / chafed / bent wires, wiring pins bent/loose, burnt appearance, and/or crossed wires. Repair or replace as required. This would be a good idea to visually check the wiring for all of the sensors.
Check for exhaust leaks, repair as necessary.
Using a digital volt ohm meter (DVOM) set to ohms, check harness connector(s) for resistance. Compare to manufacturer specifications. Replace or repair as required.
If you have access to an advanced scan tool, use it to monitor the sensor readings as viewed by the PCM (engine running, at normal operating temperature in closed loop mode). Watch the bank 2, sensor 2 reading. The rear heated oxygen sensor (HO2S) normally sees a fluctuating voltage between 0 & 1 volt, for this DTC you’ll likely see the voltage “stuck” at 0V. Revving the engine should cause the sensor’s voltage to change (react).
The most common fixes for this DTC seem to be either an exhaust air leak, a wiring problem with the sensor/wiring, or the sensor itself. If you replace the O2 sensor, buy an OEM one (manufacturer brand) for best results.
If you remove the HO2S oxygen sensor, inspect it for contamination from fuel, engine oil, and coolant.
Other troubleshooting ideas: Use a fuel pressure tester, check the fuel pressure at the Schrader valve on the fuel rail. Compare to manufacturers specification. Inspect the purge solenoid valve. Inspect fuel injectors. Inspect coolant passages for leaks.
There may be technical service bulletins (TSBs) that apply to your make and model pertaining to this trouble code, check with your dealership service department or online source to locate any specific TSBs that apply to your vehicle.
Diagnostic Video
Here is a video that pertains to a Ford O2 sensor circuit test. Case here is a 2005 Mercury Sable with a P2270 code (same DTC but for bank 1 versus bank 2), the procedure would be similar for other makes/models. We are not affiliated with the producer of this video:
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