how to test oxygen sensor
- Thread starter pustieboy
- Start date
What tools do you have the easiest way is to with a diagnostic tool connected spray some brake cleaner etc in the intake to force it rich by watching the o2 readings you can see if it’s working properly also a resistance check of the heater circuit will need doing they normally fail open circuit.
If you have an EP6 engine then that has a wide band O2 sensor and, to my knowledge, you cant monitor the out put directly with a multi meter. If you don't have an EP6 engine let us know (I'm not really a Peugeot guy, LOL).
I would recommend that you get a cheap OBDII scanner (about $30 from EBay) and go to the "short term fuel trims" in the scanner's menu.
Then do as dmccurtayne says.
The short term fuel trim should sit around 0% (+- 5 or so %) at a stable idle and engine warmed up. The numbers might move around a bit but just take your best guess at an average. The fuel trim will go negative when you spray into the inlet, if the Oxy sensor is working. It will then go positive when you stop spraying, then stabilize at about 0 again.
If the trim does not move, or stays at about 20+% positive OR negative, then you MIGHT have a dead oxy sensor. There are other things that can cause that, but one thing at a time.
The cheap OBDII scanners have VERY limited functionality, BUT, they can be helpful for diagnosing engine faults. For the 30 odd bucks they are worth it (for engine faults ONLY).
Narrow band oxy sensors can be tested with a butane, propane or MAP gas torch and a multimeter or you can use a multimeter on the car.
Narrow band sensors only have 4 wires, Wide band sensors have 5 or more wires.
Too much information for a simple question?
Why do you want to test the oxy sensor?
I would recommend that you get a cheap OBDII scanner (about $30 from EBay) and go to the "short term fuel trims" in the scanner's menu.
Then do as dmccurtayne says.
The short term fuel trim should sit around 0% (+- 5 or so %) at a stable idle and engine warmed up. The numbers might move around a bit but just take your best guess at an average. The fuel trim will go negative when you spray into the inlet, if the Oxy sensor is working. It will then go positive when you stop spraying, then stabilize at about 0 again.
If the trim does not move, or stays at about 20+% positive OR negative, then you MIGHT have a dead oxy sensor. There are other things that can cause that, but one thing at a time.
The cheap OBDII scanners have VERY limited functionality, BUT, they can be helpful for diagnosing engine faults. For the 30 odd bucks they are worth it (for engine faults ONLY).
Narrow band oxy sensors can be tested with a butane, propane or MAP gas torch and a multimeter or you can use a multimeter on the car.
Narrow band sensors only have 4 wires, Wide band sensors have 5 or more wires.
Too much information for a simple question?
Why do you want to test the oxy sensor?
The EP6 engine uses a wide band sensor., as ozVTR mentions.
These have an internal measurement cell and a pumping cell. The computer is sensing the pumping voltage, which has to become steady at 450 mV to balance O2 content on each side of the cell. The engine computer converts the electrical consumption of the pump (mA) needed to equalise into a lambda value. It isn't a simple reading as in a narrow band unit.
There is a sectional drawing with little discussion at https://www.bosch-mobility.com/en/solutions/exhaust-gas-treatment/wideband-lambda-sensor/
There is a good discussion of the similar VW sensor at http://www.techtalk.ie/wp-content/uploads/2020/12/WIDE_BAND_LAMBDA.pdf
These have an internal measurement cell and a pumping cell. The computer is sensing the pumping voltage, which has to become steady at 450 mV to balance O2 content on each side of the cell. The engine computer converts the electrical consumption of the pump (mA) needed to equalise into a lambda value. It isn't a simple reading as in a narrow band unit.
There is a sectional drawing with little discussion at https://www.bosch-mobility.com/en/solutions/exhaust-gas-treatment/wideband-lambda-sensor/
There is a good discussion of the similar VW sensor at http://www.techtalk.ie/wp-content/uploads/2020/12/WIDE_BAND_LAMBDA.pdf
Not all ep6 have wide band sensors