Signal Too Low
Signal too low
Checking the function of the flame sensor
- Ignition on.
Note! On cars where the heater functions as a parking heater there is no +15 voltage supply to the control module. The heater is activated using the timer stop and start buttons instead of VIDA vehicle communication. Individual components and functions cannot be activated when the +15 voltage supply is absent.
- Activate the heater.
For information about how the heater should operate when running, see Test running the additional heater / parking heater Initial Inspection and Diagnostic Overview.
Does the heater start?
Yes - Intermittent fault
No - Checking components and wiring
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Checking components and wiring
Check the cable between control module terminal #8 and the signal cable. Check for the flame sensor for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
Hint: It is difficult to differentiate between the ground lead for the flame sensor and the signal cable. Take readings on one cable at a time to check for a relevant value on either of them.
Replace the flame sensor if no fault is found in the cable.
Remedy as necessary.
Other information:
- To access the control module or connect the breakout box,
- To access or replace the flame sensor, see Overheating protection thermostat, flame sensor and Coolant temperature sensor, replace Replacing Overheat Protection, Thermostat Flame Sensor And Coolant Temperature Sensor
- For other values, see Signal specification Additional heater 912-D/B Signal Specification Additional Heater 912-D/B.
Select Continue.
Continue - Verification
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Verification
Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off
- Reinstall the connectors, components etc.
- Ignition on.
Note! On cars where the heater functions as a parking heater there is no +15 voltage supply to the control module. The heater is activated using the timer stop and start buttons instead of VIDA vehicle communication. Individual components and functions cannot be activated when the +15 voltage supply is absent.
- Activate the heater.
Check the function of the heater according to Test running the additional heater / parking heater Initial Inspection and Diagnostic Overview.
Does the heater operate?
Yes - VERIFIED
No - VERIFICATION FAILEDPAPER
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VERIFIED - FAULT FOUND
VERIFICATION FAILED - Fault-tracing information
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Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - FAULT-TRACING FAILED
No - Attempt New Test
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FAULT-TRACING FAILED - FAULT-TRACING FAILED
Attempt New Test - Checking the function of the flame sensor
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Intermittent fault
Check the cable between control module terminal #8 and the signal terminal for the flame sensor. Check for an intermittent short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
Remedy as necessary.
Other information:
- To access the control module or connect the breakout box,
- For other values, see Signal specification Additional heater 912-D/B Signal Specification Additional Heater 912-D/B.
Select Continue.
Continue - Fault-tracing information
DONE
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Fault-tracing information
Information
Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).
Do you want to view the information again?
Yes - Attempt New Test
No - FAULT FOUND
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Attempt New Test - Checking the function of the flame sensor
FAULT-TRACING FAILED - DONE
FAULT FOUND - FAULT FOUND
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