Signal Too High
Signal too high
Diagnostic trouble code (DTC) status ECM-1200, Intake air temperature (IAT) sensor. Signal too high
Reading off diagnostic trouble code (DTC) status ECM-1200
Note! When reading off the diagnostic trouble code (DTC) status, other stored diagnostic trouble codes (DTCs) and their status will be listed.
- Read off the diagnostic trouble code (DTC) status. Check the status of the relevant diagnostic trouble code (DTC).
Was the status of the relevant diagnostic trouble code (DTC) permanent?
Yes - Checking the connector
No - Intermittent fault
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Intermittent fault
Signal too high. Intermittent fault
Checking wiring and connectors
Check the control module and mass air flow (MAF) sensor connectors for contact resistance and oxidation according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults. Also check for loose connections according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults. The intake air temperature (IAT) sensor is integrated in the mass air flow (MAF) sensor.
Check the signal cable between control module connector terminal A4 (#A4) and mass air flow (MAF) sensor connector terminal 3 for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults. Also check for an intermittent short-circuit to supply voltage according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check the ground lead between control module connector terminal A61 (#B3) and mass air flow (MAF) sensor connector terminal 4 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 / replace the control module see
- To access / replace the Mass Air Flow (MAF) sensor, see
- 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 - Checking wiring and connectors
DONE - DONE
FAULT FOUND - DONE
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DONE - DONE
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Checking the connector
- Ignition off.
- Check the mass air flow (MAF) sensor connector for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault The intake air temperature (IAT) sensor is integrated in the mass air flow (MAF) sensor.
Other information:
- To access / replace the mass air flow (MAF) sensor, see
- For information about signals, see Signal specification Signal Description / Specification.
Is the signal OK?
Yes - Verification
No - Checking the intake air temperature (IAT) sensor signal
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Checking the intake air temperature (IAT) sensor signal
- Ignition on.
- Engine running.
- Read off the intake air temperature (IAT) sensor signal.
Check that the signal is OK according to the table value: Intake air temperature (IAT) sensor inlet Intake Air Temperature (IAT) Sensor Inlet.
If the signal is now OK, the fault was caused by poor contact in the connector.
Other information:
- To access / replace the mass air flow (MAF) sensor, see
- For information about signals, see Signal specification Signal Description / Specification.
Is the signal OK?
Yes - Verification
No - Checking wiring and components
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Checking wiring and components
Check the intake air temperature (IAT) sensor voltage between terminals 3 and 4 on the mass air flow (MAF) sensor. The intake air temperature (IAT) sensor is integrated in the mass air flow (MAF) sensor. For voltage values, see Intake air temperature (IAT) sensor inlet Intake Air Temperature (IAT) Sensor Inlet.
Check the signal cable between control module connector terminal A4 (#A4) and mass air flow (MAF) sensor connector terminal 3 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Also check for a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Hint: With the ignition on and the mass air flow (MAF) sensor connector disconnected, the voltage between terminal 3 and the ground terminal should be approximately 5V.
Check the ground lead between control module connector terminal A61 (#B3) and mass air flow (MAF) sensor connector terminal 4 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Remedy as necessary.
Other information:
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box
- To access / replace the control module see
- To access / replace the mass air flow (MAF) sensor, see
- For information about signals, see Signal specification Signal Description / Specification.
Continue - Verification
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Verification
Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off.
- Reconnect the connectors, reinstall components etc.
- Ignition on.
- Read off Intake Air Temperature (IAT) sensor signal. The Intake Air Temperature (IAT) sensor is integrated into the Mass Air Flow (MAF) sensor.
Check that the signal is OK according to the table value: Intake air temperature (IAT) sensor inlet Intake Air Temperature (IAT) Sensor Inlet.
Is the signal 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 - Intake air temperature (IAT) sensor. Signal too high
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