Hey guys, running in to a wall here. Getting errors related to the B1S1 O2 Sensor, Lean at idle code

2006 Mazda 5, 4 cyl

New O2 Sensors installed
Wiring to O2 Sensors Checked
MAF Reading at Idle 1.94 - 2.6 G/S
Bar Pressure 103KPA (Which a little above sea level is normal)
Intake manifold pressure 43kpa

Getting voltage readings on the O2 Sensor .02, jumping around a little but it is .05 or below when it should be .9 or so.

Idle at about 750 RPM, no vacuum leaks that I can take note of.

New Spark Plugs installed.

I checked the PCV, Intake, Vacuum lines from the EVAP, Intake hoses, can't seem to find a source of the leak.

I hear a slight hiss from the device shown in the pic but not sure what it is, the hose from it and to the throttle body is not leaking however.

Any ideas? Appreciate any feedback.

 

Bank1 Sensor 1 is the A/F sensor - Air fuel.

Did you replace the sensor in the Manifold or the actual O2 sensor in/ or behind the catalytic convertor?

What was the actual fault code?

The sensor is only a monitor of engine operation. If the engine isn't operating perfectly, you will get these codes. Yes the sensors can fail, but you need to carry out diagnosis before throwing parts at your car.

 

The parts were replaced prior to me getting the vehicle. They replaced both O2 Sensors. I tested and checked the wiring and performing diagnostics now and no issue found. I am still betting on a vacuum leak causing a lean condition. I don't believe the problem was with the O2 sensor but again they were replaced by the PO. I will get the current code.

 

P2187

 

DTC P2187 Fuel system too lean at idle



DETECTION CONDITION

• PCM monitors short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) during closed loop fuel control at idle. If the LONGFT or the sum total of these fuel terms exceed preprogrammed criteria. PCM determines that fuel system is too lean at idle.
Diagnostic support note
• This is a continuous monitor. (FUEL SYSTEM)

• MIL illuminates if PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in the PCM memory.


POSSIBLE CAUSE

• Misfire

• Front HO2S deterioration

• Front HO2S heater malfunction

• MAF sensor malfunction

• Pressure regulator (built-in fuel injection pump) malfunction

• Fuel pump malfunction

• Fuel filter clogged or restricted

• Fuel leakage on fuel line from fuel delivery pipe and fuel pump

• Leakage exhaust system

• Purge solenoid valve malfunction

• Purge solenoid hoses improper connection

• Air suction in intake-air system

• Insufficient engine compression

• Variable valve timing control system improper operation (L3)

 

Ran a smoke test and see a leak from this device but not even sure what it is. Can someone identify it?

 

Found it, EGR.

 

Looks like the EGR to me.

I hope people can learn from this, Just because there is a O2 code, it doesn't automatically mean the O2 sensor is faulty.