My Service Engine Soon Light came on, so I took it to a Napa store and they did a check on it. The results were: AF Sensor Lean Shift Detected Failed AF Sensor Vacuum Leak in Engine Fuel Injector or Pressure Regulator Fault So what does this mean, could it possibly just need a new air filter?

make sure they are plugged in tight Definition of Diagnostic Trouble Code P2270 Category: Powertrain Definition: O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2Note: This definition of P2270 is applied to all manufacturers

P2270 - O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2 Comments ' Add Yours
Possible causes
- Faulty Rear Heated Oxygen Sensor Bank 1
- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Exhaust gas leaks Help with this
When is the code detected?
The Powertrain Control Module (PCM) detected the HO2S12 sensor has reported a lean condition for an extended period during an intrusive test
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
P2270 Description
The Powertrain Control Module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCMevaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.

Definition of Diagnostic Trouble Code P2272 Category: Powertrain Definition: O2 Sensor Signal Biased/Stuck Lean Bank 2 Sensor 2Note: This definition of P2272 is applied to all manufacturers

P2272 - O2 Sensor Signal Biased/Stuck Lean Bank 2 Sensor 2
' Add Comment
Possible causes
- Faulty Rear Heated Oxygen Sensor Bank 2
- Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection
- Exhaust gas leaks
What does this mean?
When is the code detected?
The Powertrain Control Module (PCM) detected the HO2S22 sensor has reported a lean condition for an extended period during an intrusive test
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
P2272 Description
The Powertrain Control Module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCMevaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.
P2272 Information for specific makes
P2272 BMW
P2272 DODGE
P2272 FORD

Check for loos connections between the intake and the tube from the air filter. Check if the clamp is loose or leaks in the tube which can cause an incorrect reading. Other than that it may be a dirty MAF sensor which can be fixed by spraying carb cleaning or tuner spray in the intake or it may be bad or a bad oxygen sensor;.

Fault Code 51 - Oxygen sensor output indicates lean too long

Power loss light: Off
Limp-in mode: Engine allowed to run rich, but prevented from running lean

Possible Causes
Bad oxygen sensor - Replace the sensor which is located on the turbo housing near the down pipe (for turbo) or on the down pipe near the exhaust manifold.

Bad connection or wiring - Check the wiring and connections between the sensor and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease and repair any shorts. Look for melted wire insulation near the exhaust manifold. A shorted connection to ground or any positive source will cause this fault code.

Low fuel rail pressure - See the Diagnosing Your Fuel System page.

Diagnostic Method - Trigger Parameters
- In closed-loop
- Sensor output indicates lean for more than 715 seconds (11 minutes, 55 seconds)

Results If Component Fails
A fault code 51 is stored, the circuit stays in closed-loop, and the logic module will still monitor the oxygen sensor signal. If the condition persists for four times what it took to set the code, the logic module will allow the engine to run rich, but prevent it from running lean.

Hope helps.

O2 sensors both but couldnt tell you if its upstream or down stream.

Likey a sensor not connected completely or a vacuum line disconnected. go to your local Napa or simalar parts store & have them read the code that will point you in the right direction. if it's not flashing you should be ok to drive.

No I don't think so, knock sensor only work under engine load, when sensor picks up a ping or knocking, it will adjust timing, o2 sensor could be bad, and will save you fuel mileage, but a miss will also give you an o2 sensor code, running rich, have him check for cylinder miss first.

you need to change the oxygen sensor. it will soon cause you problems. after you need to take it in to  erase the code.

codes are for fuel system lean bank 1 and 2. low fuel pressure or innacurate mass air flow sensor could cause this. most common is mass air flow sensor.

HI
the (P1273) refer to A\F SENSOR
that locate in the exhaust pipe
it was a sensor calculate the air to fuel ratio in the exhaust pipe and send that as electrical signal to the (ECU) that use it to correct the fuel injection timing in result to have economy of fuel and low bad gases in exhaust
the cause of this fault is :-
air fuel ratio sensor 1
air fuel ratio sensor 1 heater
fuel presser
fuel injectors
intake air leaks

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