European On-Board Diagnosis (EOBD) CDI function - GF07.16-P-3200T

ENGINE 642.920 in MODEL 211.020/024/220/620, 219.322 

ENGINE 642.921 in MODEL 211.084/089/284/289 

ENGINE 642.920 in MODEL 211.022 except CODE (494) USA version 

ENGINE 642.920 in MODEL 211.022/222 except CODE (498) Japan version 

Shown on model 211 

European On-Board Diagnosis (EOBD) has the following tasks:

• Monitoring emission-relevant components and systems during driving
• Determining and storing malfunctions
• Display of malfunctions via the engine diagnosis indicator lamp
• Transfer of detected faults to STAR DIAGNOSIS

The following systems and functions are electronically monitored:

• Exhaust gas recirculation (EGR)
• Smooth running control (cylinders 1 to 6)
• Fuel system
• Glow system
• Intake and charge air system

Readiness code 

This code makes it possible to recognize that test procedures (function chains) relating to fault recognition have been completed.

The readiness code detects the following electronic systems:

• AGR
• Fuel system
• Smooth running control

The readiness code is set when two driving cycles, including a cold start, have taken place without error.

Warm-up cycle 

Systems that are not constantly monitored are checked only when a warm-up cycle is executed.

A warm-up cycle consists of the following sub-cycles:

• Engine start
• Temperature increase > 4.5°C
• Final temperature > 60°C
• Engine switch-off
• Computer run-on at least 10 seconds (wait for cooling fan run-on)

Driving cycle 

One driving cycle consists of:

• Engine start
• 35 s at idle
• Engine switch-off
• Computer run-on at least 10 seconds (wait for cooling fan run-on)

The CDI control unit checks its input and output signals for plausibility and recognizes possible faults.

Fault recognition 

The following faults and error states are detected:

• Signals over or below the limit value (e.p. line open circuit, short circuit, defective sensor)
• Fault messages over Controller Area Network (data bus/CAN bus) (CAN), from CDI control unit and from fully integrated transmission control (VGS) control unit (Y3/8n4) for vehicles with transmission 722.9
• Plausibility of signals
• Function chains with faults

Fault storage 

Faults detected are stored in the fault memory of the CDI control unit together with freeze frame data. If the fault is not confirmed during the following driving cycle, it is deleted. Emission-relevant faults are always entered, they have a high priority.

Following 40 fault-free driving cycles, an exhaust gas relevant fault is deleted from the fault memory.

Fault freeze frame data and operating conditions 

If a fault is detected, the following freeze frame data is saved in addition to the fault code:

• Vehicle speed
• Engine speed
• Coolant temperature
• Charge air temperature
• Boost pressure
• Engine load status

Consequential faults 

If a faulty signal is detected and the corresponding fault code is stored, all the tests in which the signal is required as a comparative parameter, are ended. This ensures that no consequential faults are stored.

Read out the fault memory 

Stored faults can be read out using STAR DIAGNOSIS at status "Circuit 15 ON" or at status "Circuit 61 ON" via the data link connector. The fault memory can only be cleared for "Circuit 15 ON".

The fault memory is not erased if the battery (G1) is disconnected.

CDI control unit power-down 

After faults are erased, it is necessary to wait until the processor has completed its power-down sequence after Circuit 15 is switched off. The processor power-down sequence lasts max. 10 s. If the cooling fan run-on is active, it is necessary to wait for the run-on time to complete.

Component description for the CDI control unit

N3/9

GF07.16-P-6000T