Signal Too Low
Signal too low
Checking software
Checking software
Checking software
Note! The information below only applies to modal year 2003-2004.For other model years, select the alternative "No".
It may be possible to remedy the fault by downloading new software into the control module.
Action
- Go to the tab software and program the control module with the latest software.
Other information
- For more information, see Design and Function.
Has the fault been remedied?
Yes - Fault Found
No - No Fault Found
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FAULT FOUND - Fault Found
No Fault Found - front heated oxygen sensor (HO2S), control
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DTC status ECM-2120, front heated oxygen sensor (HO2S), control
Note! When reading off the DTC status, other stored diagnostic trouble codes (DTCs) and their status will be listed.
Read off the DTC status. Check the status of the relevant Diagnostic Trouble Code (DTC).
Was the status of the relevant Diagnostic Trouble Code (DTC) displayed as permanent?
Yes - Checking connector
No - Checking cables
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Checking cables
Check front heated oxygen sensor (HO2S) connector for contact resistance and oxidation according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check signal cable (+) between control module #A42 and heated oxygen sensor (HO2S) connector terminal 4 for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check signal cable (-) between control module #A41 and heated oxygen sensor (HO2S) connector terminal 3 for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Other information
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access the control module, see
- To access/replace the heated oxygen sensor (HO2S), see Heated oxygen sensor (HO2S), replacing Heated Oxygen Sensor (HO2S), Replacing
- For information about signals, see Signal specification Signal Description / Specification.
Continue - Fault-tracing information
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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 - front heated oxygen sensor (HO2S), control
FAULT FOUND - DONE
DONE - DONE
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Checking connector
- Ignition off.
Check front heated oxygen sensor (HO2S) connector for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Caution! Do not apply rust solvent spray or grease to the heated oxygen sensor (HO2S) connector.
Remedy as necessary.
Other information
- To access/replace the heated oxygen sensor (HO2S), see Heated oxygen sensor (HO2S), replacing Heated Oxygen Sensor (HO2S), Replacing
- For information about signals, see Signal specification Signal Description / Specification
Continue - Checking connector
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Checking connector
- Ignition off.
- Reinstall components, reconnect connectors etc.
- Start the engine and let it idle.
- Read off the lambda value for the rear heated oxygen sensor (HO2S).
Note! It takes approximately 25 seconds before fuel trim starts.
Check that the value is within its permitted range. The value should be approximately 0.98 and 1.02.
If the value is now OK it means that the cause of the fault has been loose connections in connector.
Other information
- To access/replace the heated oxygen sensor (HO2S), see Heated oxygen sensor (HO2S), replacing Heated Oxygen Sensor (HO2S), Replacing
- For information about signals, see Signal specification Signal Description / Specification.
Is the value OK?
Yes - Fault Found
No - Checking wiring and components
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Checking wiring and components
Caution! Do not apply rust solvent spray or grease to the heated oxygen sensor (HO2S) connector.
Check signal cable (+) between control module #A42 and heated oxygen sensor (HO2S) connector terminal 4 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Hint: With the ignition on and heated oxygen sensor (HO2S) connector disconnected, the voltage between terminal 4 and ground terminal should be approximately 3.8 V.
Check signal cable (-) between control module #A41 and heated oxygen sensor (HO2S) connector terminal 3 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
If wiring is OK, try another heated oxygen sensor (HO2S).
Remedy as necessary.
Other information
- Connecting the breakout box/accessing the control module, see
- To access/replace the heated oxygen sensor (HO2S), see Heated oxygen sensor (HO2S), replacing Heated Oxygen Sensor (HO2S), Replacing
- For information about signals, see Signal specification Signal Description / Specification.
Continue - Verification
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Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off.
- Reconnect connectors, reinstall components
- Start the engine and let it idle.
- Read off the lambda value for the rear heated oxygen sensor (HO2S).
Note! It takes approximately 25 seconds before fuel trim starts.
Check that the value is within its permitted range. The value should be approximately 0.98 -1.02.
Is the value OK?
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 - FAULT-TRACING FAILED
No - Attempt New Test
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FAULT-TRACING FAILED - FAULT-TRACING FAILED
Attempt New Test - front heated oxygen sensor (HO2S), control
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