Signal Too Low - Permanent Fault

ECM-1200 INTAKE AIR TEMPERATURE (IAT) SENSOR INLET
SIGNAL TOO LOW - PERMANENT FAULT

Checking connector



- Ignition off
- Check intake air temperature (IAT) sensor connector for contact resistance and oxidation according to [1][2]Checking Wiring and Terminals. Permanent Fault.
- Reinstall components, reconnect connectors etc.
- Ignition on.
- Read Intake Air Temperature (IAT) sensor signal.

Check that the signal is within its permitted range.
The voltage can vary between 0.17 V and 4.9 V depending on air temperature. At 20°C (68°F) voltage should be approximately 3.5 V.
If signal is now OK this indicates that the fault was caused by poor contact in the connector.

Other information
- To access/replace the Intake Air Temperature (IAT) sensor, Intake Air Temperature Sensor, Replacing

Is the signal OK?
Yes - Testing Complete.
No - Continue below.


Checking wiring and components



Check the Intake Air Temperature (IAT) sensor resistance.

NOTE: The Intake Air Temperature (IAT) sensor can be defective if the signal cable has been short-circuited to supply voltage. Check this before replacing the sensor.

Check signal cable between control module #A5 (#A5) and intake air temperature (IAT) sensor connector #1 for an open-circuit according to [1][2]Checking Wiring and Terminals. Permanent Fault and a short-circuit to supply voltage according to [1][2]Checking Wiring and Terminals. Permanent Fault

Hint: With the ignition on and intake air temperature (IAT) sensor connector disconnected voltage between # 1 and ground terminal should be approximately 5 V.

Check the ground lead between control module #A60 (#A60) and intake air temperature (IAT) sensor connector #2 for an open-circuit according to [1][2]Checking Wiring and Terminals. Permanent Fault

Remedy as necessary.

Other information
- Connecting the breakout box/accessing the control module, Connecting the Breakout Box (ECM)
- To access/replace the Intake Air Temperature (IAT) sensor, Intake Air Temperature Sensor, Replacing
- For information about signals, see Diagnostic Parameters and Pinout Values. Signal Description, ME7, B5XX4T


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 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.




Is the signal OK?
Yes - Testing Complete.
No - Continue below.


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.