Status Parameter - Test Results

[Martin Rubenstein]

I’ve opened this thread to put my tests on Status in one place, Status being the parameter in Al’s MEMSAnalyser on the Lambda page.

Status seems to be a monitor of both the heater circuit and the signal circuit. Status should be 1 all the time; if it starts at 1 and falls to zero within a minute of the engne starting, there is a fault in the heater circuit, the sensor circuit or both.

1. Heater circuit working, lambda signal circuit
open: Status dropped to zero within a minute of engine start. Bias voltage 0.435V all the time.

2. Lambda signal circuit shorted to ground (heater working): Status drops to zero within a minute of engine start. Bias voltage zero all the time.

3. Sensor connector disconnected. Status drops to zero within a minute of engine start. Bias voltage is 0.435V all the time.

4. Coolant temperature 60C, and heater relay removed to disable the lambda heater. Status drops to zero within a minute with high engine revs. Lambda voltage 0.435V all the time with no lambda activity.


5. Heater diconnected. Hot engine 85C and engine restarted after 3 mins, Status drops to zero within a minute. Lambda voltage stays at 0.435V all the time.


6. Heater disconnected. Hot engine 85C ignition turned off for only 45sec before restarting. Status stays at 1 and lambda voltage shows up/down activity but it is abnormally slow switching frequency.


Effect of RPM on Time for Status to Drop under Fault Conditions.

With fault present, time for Status to fall to zero after engine start depends on RPM. Left at idle, Status falls to zero in 45sec. At 2000-3000RPM, Status takes 20sec to drop to zero after engine start.


How ever it works, Status seems to be a very clever and valuable indicator of the integrity of the complete oxygen-sensing system.

[Martin Rubenstein]

With coolant temperature sensor disconnected, so ECU assumes a (limp home) value of 60C, the Staus parameter drops to zero within a minute of engine start, even though the oxygen sensing circuit is good. (At a fast idle of 2000rpm, Status dropped to zero at 23 secs after engine start.). The ECU stayed in open loop even though lambda voltage was changing and being shown in MEMSAnalyser as varying

This appears to show that Status doesn’t just indicate the workings of the lambda circuits but it’s indicating if there’s a fault that will send the car into open loop, limp home. And it shows that even if the car is in open loop, so long as the oxygen sensor is good, the lambda voltages will be measured by the ECU and displayed by the software.