Gaziantep Oxygen Sensor Fault
Oxygen / lambda sensor · GaziantepAn oxygen sensor warning usually does not mean the sensor is broken, but that the mixture is not in the expected range. That distinction has to be made before replacing the sensor.
What does the lambda sensor do?
The lambda sensor measures the oxygen level in the exhaust and tells the control unit whether the mixture is rich or lean. With that information the control unit continuously corrects injection duration.
The sensor before the catalyst is used for mixture control, the one after it to monitor whether the catalyst is working. Because they do different jobs, their data is also interpreted differently.
Oxygen sensor fault symptoms
- Engine warning light
An entry relating to the sensor circuit or to fuel trim.
- Rising fuel consumption
Consumption rises when fuel trim goes wrong.
- Rough idle
Becomes noticeable particularly when running cold.
- Delayed response
The engine responding late when the throttle is opened.
- Exhaust smell
A clear smell of unburnt fuel with an over-rich mixture.
- Emissions figures out of range
Values measured at inspection falling outside the limits.
What should be checked before replacing the sensor?
In a good share of the faults that produce a sensor code, the sensor itself is fine. The order is as follows:
- Exhaust leak
A leak before the sensor lets air in from outside and produces a lean reading.
- Air / fuel mixture
An intake leak, a dirty air filter or a drifting mass air flow sensor upsets the mixture.
- Fuel system
Low fuel pressure or dirty injectors make it lean; a leaking injector makes it rich.
- Wiring
The heater circuit, signal wire and ground connection are measured.
- Sensor live data
Sensor response speed and signal amplitude are assessed to see whether it has aged.
- Ignition side
A misfire on one cylinder leaves unburnt oxygen in the exhaust and produces a lean entry.
How do we assess the oxygen sensor?
Sensor data is not read on its own but together with the other values that affect the mixture.
- Code and bank identification
Which bank and which sensor position the code belongs to is established.
- Fuel trim values
Short and long term trims are compared at idle and under load.
- Signal behaviour
Sensor response speed and switching are monitored in real time.
- Leak check
Leaks are looked for on the intake and exhaust sides.
- Heater circuit measurement
The sensor heater resistance and the supply circuit are checked.
- Verification
After repair, a road test confirms that the trim values have returned to the normal range.
How is the solution decided?
With a lambda code, the solution becomes clear once it is established whether the sensor or the mixture is the problem.
- Exhaust leak repair
Without fixing a leak before the sensor, the reading cannot be right.
- Fixing the mixture problem
If the cause is an intake leak, the mass air flow sensor or the fuel side, that is solved first.
- Heater circuit repair
Repaired if the sensor heater or the supply circuit is faulty.
- Sensor replacement
Renewed if response speed and signal behaviour show the sensor has aged.
- Adaptation
Afterwards it is verified that the fuel trim values have returned to normal.
Related fault topics
Lambda and mixture entries in the fault memory do not always mean the sensor is broken.
Gaziantep oxygen sensor solution
To separate by measurement whether a lambda sensor code is the sensor or the mixture in Gaziantep, get in touch with Nero Performance.