The 2D0 unit has 5 LEDs designed to provide simple and precise status reporting. Normally just the single red status LED is presented to the user, or, additionally the green power LED.
The two outside LEDs, ie. the green power (PWR) and amber heater (HEAT), LEDs work as for other WBo2 units. The red status (STAT) and two error (ERR1, ERR2) LEDs are quite different and their operation is described below.
Note 1: In your equipment using the 2D module, the PWR and STAT LEDs may be installed off the PCB, so we normally leave these LEDS off so two optional 0.1" headers can be installed for use with the LEDs mounted remotely.
Note 2: The image of the 5 LEDs below right is how the LEDs are normally placed on the PCB. It is possible to use different colours. Remember that the descriptions below refer to the standard colour placements.
As for other WBo2 units, the power LED (normally installed as a GREEN LED) is ON when there is power to the WB unit. The heater LED is amber and flashes reasonably brightly at 30 Hz (30 times/second) when functioning normally. If the sensor is not connected, or there is a battery error, then the amber LED will only flash dimly or will have a very short ON flash at a few times a second to indicate the firmware's attempt to find the sensor.
The status LED is normally constructed to have a red LED to be compatible with other WBo2 unit. Instead of the simple flashing error code of the other units, 2D0 uses from zero to 6 repeating flash sequences to indicate normal or error status. There is a one second pause between sequences, and the flashes lasts 0.1 sec with a 0.25 sec between flashes.
Unit is not powered, or if green LED is ON, processor is non-operation
LED on steady, unit is functional within normal parameters
Sensor is in warmup cycle (normally last 20 to 30 seconds).
Sensor is not connected (or open sensor heater circuit)
Battery voltage is less then 10.5 Volts, higher than 19.5 Volts, or there's a FET error
heater circuit is shorted out
Sensor is operational but cannot be heated to optimal temperature range
Sensor is operational but is above maximum optimal temperature range
During the normal operational state, where no hardware or battery voltage errors occur, the two amber LEDs provide extra information as detailed below. PID is an abbreviation that refers to how the control firmware operates. There are two firmware PIDs in WBo2, one for the heater, and one for the Lambda function. The two error LEDs report PID conditions that are caused by the sensor getting too hot or colder than it can compensate for, or the Lambda part of the sensor seeing a AFR (Lambda) that is either changing faster than it can track it, or is out of normal operating bounds (too rich).
Normal operation, no PID conditions to report
Lambda PID tracking lag
Lambda PID inaccurate
Heater PID tracking lag
Heater PID inaccurate
Normally, when the sensor is positioned where it's not too hot, not too cold, nor subject to excessively rich mixtures, then these transitory conditions should not persist. If they do then there may be a problem with the sensor's placement, or it has naturally aged, or it has become contaminated and is very sluggish.
During the time the sensor is warming up, a number of conditions will be shown on the two error LEDs. When the indicated condition is fixed, and the sensor is warmed, the LEDs indicate the conditions in the previous table.
Warm up state
Heater open circuit or sensor/cable disconnected
Heater short - bad cable or sensor damaged
Battery voltage is too high (>19.5) or low (< 10.5)
FET error - Internal switching error detected