Signal Too Low

Signal too low

Checking the status




- The ignition must be on to perform the diagnostic.
Check whether the fault is permanent or intermittent. Read off the diagnostic trouble code (DTC) fault status when the diagnostic status is "Completed".
The fault is permanent if the fault status is "Fault found". The fault is intermittent if the fault status is "No fault detected".










Continue - Checking fuses

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Checking the components and wiring

Caution! Do not apply rust solvent spray or grease to the heated oxygen sensor (HO2S) connector.

Note! Diagnostic trouble code (DTC) may be caused by a damaged fuse.

Check the cable between heated oxygen sensor (HO2S) terminal #1 and the power supply from the system relay. Check for an open-circuit. Check for a short-circuit to ground.
Try a new heated oxygen sensor (HO2S) if the above fault-tracing does not remedy the fault.
Remedy as necessary.

Other information
- Signal specification Signal Specification, Engine Control Module (ECM)
- Oxygen sensor (Catalyst monitor sensor) Oxygen Sensor (Catalyst Monitor Sensor)
- Checking wiring and terminals Checking Wiring and Terminals














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.
- The ignition must be on to perform the diagnostic.

Note! The battery voltage must be between 11-16V in order to obtain a correct reading.

Read off the diagnostic status and the fault status for the diagnostic trouble code (DTC).
Check that the diagnostic is "Completed" and that the fault status is "No fault detected". The function is faulty if the fault status is "Fault found".





Is the fault status "No fault detected"?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFICATION FAILED - Fault-tracing information

VERIFIED - Fault Found

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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 - Exit Fault-Tracing

No - Attempt New Test

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Attempt New Test - Checking the components and wiring

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Checking fuses
All heated oxygen sensors are supplied with voltage with the same lead. If the lead is damaged, e.g., fuse on the lead, then diagnostic code for heating for all heated oxygen sensors will be stored.
Therefore, check first if diagnostic trouble codes for heating are also stored for other heated oxygen sensors.

Hint: Brake vacuum pump is supplied with voltage via the same lead as the heated oxygen sensors. A damaged brake vacuum contact can lead to the pump running continuously and in the long-term be overheated and damaged. In turn, this leads to damaged fuse.
Therefore, check the brake vacuum switch and pump before any continued troubleshooting is done on the heated oxygen sensors.

Continue.

Continue - Checking the components and wiring

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