Intake Air Oxygen Sensor
An oxygen sensor mounted in the intake rather than the exhaust, and the reason it is there is genuinely elegant. Recirculated exhaust gas has had its oxygen burned out of it; fresh air has not — so measuring the oxygen content of the intake charge says directly what proportion of it is recirculated exhaust. It measures the EGR rate rather than inferring it.
That matters because the older method compounds errors. Working the rate out from airflow and manifold pressure stacks several sensors' inaccuracies together, and modern diesels run EGR rates high enough that the imprecision costs real emissions. A sensor in the intake removes the guesswork, which is why they are appearing on engines that never had one.
It is a wideband sensor with a heater, like its exhaust cousins, and it is diagnosed the same way electrically — but do not confuse the two when reading codes: this one says nothing about fuelling or the catalytic converter.
Its position is its problem. It sits in the sootiest, oiliest part of the induction system on an EGR-equipped engine, so its connector collects exactly what the EGR valve deposits and oil mist from the breather wicks into it. Clean and dry the connector before condemning the sensor, and ask why it got dirty — a coked intake will foul a replacement the same way.
Also known as: intake oxygen sensor, intake o2 sensor, charge air oxygen sensor, egr rate sensor, intake lambda sensor
Referenced by 7 codes
Codes involving this component (7)
- P2B89 Intake Air O2 Sensor Circuit Low Voltage Bank 1 Moderate
- P2B88 Intake Air O2 Sensor Circuit Bank 1
- P2B8A Intake Air O2 Sensor Circuit High Voltage Bank 1
- P2B8B Intake Air O2 Sensor Heater Control Circuit/Open Bank 1
- P2B8C Intake Air O2 Sensor Heater Control Circuit Range/Performance Bank 1
- P2B8D Intake Air O2 Sensor Heater Control Circuit Low Bank 1
- P2B8E Intake Air O2 Sensor Heater Control Circuit High Bank 1
Other components in Air Intake and Metering
- Intake Air Temperature Sensor 83
- Throttle Body 69
- Throttle Position Sensor 58
- Intake Manifold Tuning Valve 56
- Mass Air Flow Sensor 52
- Intake Manifold 51
- EGR Throttle Valve 38
- Throttle Actuator Motor 34
- PCV Valve 31
- Air Filter 30
- Manifold Absolute Pressure Sensor 29
- Crankcase Pressure Sensor 14
- Crankcase Breather Hose 13
- Intake Air Heater 11
- Idle Air Control Valve 9
- Humidity Sensor 5
- Air Cleaner Inlet Actuator 3
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