| A/F Ratio |
Air Fuel Ratio. |
| A/F Ratio Sensor |
A four wire, heated oxygen sensor that more precisely measures A/F ratio than do traditional sensors. |
| Aftermarket Sensor |
A sensor made to replace OE sensors. |
| PCM |
Powertrain Control Module |
| ECM |
Electronic Control Module |
| CEL |
Check Engine Light. |
| Closed Loop Mode |
When the oxygen sensor(s) are operational in a vehicle’s diagnostics |
| DTC |
Diagnostic Trouble Code |
| Direct Fit Sensor |
A sensor with a connector that fits an existing connector directly. |
| DIY Installer |
Do It Yourself. An individual that works on his or her own vehicle. |
| Downstream |
The sensor position after the catalytic converter. Also known as post-cat. |
| ECU |
Engine Control Unit |
| FLO Sensor |
Fast Light Off Sensor. This design can reach operating temperature in as little as 10 seconds. |
| Heated Sensor |
An oxygen sensor design that utilizes an internal heater. |
| Lean |
A condition where there is an excess of oxygen in the exhaust stream |
| MIL |
Malfunction Indicator Lamp |
| OBDII |
The current onboard diagnostic language used by passenger vehicles. |
| OE Sensor |
A sensor that is installed on a factory vehicle |
| Open Loop Mode |
When the oxygen sensor(s) are not engaged in a vehicle’s diagnostics |
| Planar Sensor |
A sensor made of layers of zirconia & alumina bonded together, allowing for faster warm up of the sensor |
| Rich |
A condition where there is a shortage of oxygen in the exhaust stream |
| Stoichiometric |
The ideal air fuel ratio of 14.7:1 air: fuel by mass for gasoline engines |
| Titania Sensor |
A sensor design that employs the use of titanium instead of zirconia |
| UFLO Sensor |
Ultra Fast Light Off Sensor. The oxygen sensor design that will reach operating temperature in the least amount of time possible. |
| Universal Sensor |
A sensor with no connector that must be installed through splices |
| Unheated Sensor |
An early, basic sensor design that relies on external heat |
| Upstream |
The sensor position before the catalytic converter. Also known as pre-cat |
| Wideband |
A five wire, heated oxygen sensor that utilizes patented technology to provide a better measurement of A/F ratio than do four wire sensors |
| Zirconia |
A white, crystalline compound that is used in oxygen sensors |
