Signal Too High. Permanent Fault
Signal too high. Permanent fault
EFI-251 Outside temperature sensor, signal.
Checking ground lead
- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Disconnect outside temperature sensor (blue connector).
Connect an ohmmeter between outside temperature sensor connector terminal 2 and ground.
The ohmmeter should read approximately 0 ohms.
OK - Checking the signal cable
Not OK - Checking control module connector
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Checking the signal cable
- Ignition on.
- Temperature sensor disconnected.
Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module (ECM) side).
The voltmeter should read approximately 5 V.
OK - Checking temperature sensor resistance
Low - Checking control module connector
High - Checking for a short-circuit
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Checking for a short-circuit
- Check cable between outside temperature sensor terminal 1 and engine control module (ECM) #A35 for a short-circuit to voltage supply according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Checking the outside temperature sensor
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Checking control module connector
- Ignition off.
- Temperature sensor disconnected.
- Check control module connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Control module connected.
Connect an ohmmeter between temperature sensor connector terminal 2 (engine control module (ECM) side) and ground.
The ohmmeter should read approximately 0 ohms.
OK - Fault-tracing information
Not OK - Checking for an open-circuit
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Fault-tracing information
The cause of the diagnostic trouble code (DTC) has been loose connections in the control module connector.
Continue - Verification
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Checking for an open-circuit
- Check cable between temperature sensor terminal 2 and engine control module (ECM) #A18 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Checking temperature sensor resistance
- Ignition off.
- Temperature sensor disconnected.
Connect an ohmmeter between temperature sensor connector terminals 1 and 2 (temperature sensor side).
The ohmmeter should read approximately 500 ohms at +25°C (see table).
OK - Checking for contact resistance and oxidation
Not OK - Replacing component
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Checking for contact resistance and oxidation
The diagnostic trouble code (DTC) has been caused by loose connections in the outside temperature sensor connector.
- Check connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Replacing component
- Try a new outside temperature sensor.
Continue - Verification
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Checking the outside temperature sensor
Hint: The outside temperature sensor can malfunction due to a short-circuit to supply voltage in the signal cable. Check the temperature sensor as follows:
- Ignition off.
- Temperature sensor disconnected.
Connect an ohmmeter between temperature sensor connector terminals 1 and 2 (temperature sensor side).
The ohmmeter should read approximately 500 ohms at +25°C (see table).
OK - Fault-tracing information
Not OK - Replacing component
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Fault-tracing information
Temperature sensor is OK.
Continue - Verification
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Replacing component
- Try a new outside temperature sensor.
Continue - Verification
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Checking control module connector
- Ignition off.
- Temperature sensor disconnected.
- Check control module connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Control module connected.
- Ignition on.
Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module (ECM) side).
The voltmeter should read approximately 5 V.
OK - Fault-tracing information
Not OK - Checking for an open-circuit
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Fault-tracing information
The cause of the diagnostic trouble code (DTC) has been loose connections in the control module connector.
Continue - Verification
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Checking for an open-circuit
- Check cable between temperature sensor terminal 1 and engine control module (ECM) #A35 for a short-circuit to voltage supply according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied as follows:
- Ignition off.
- Reconnect connectors, reinstall components etc.
- Ignition on.
Select Volvo Scan Tool (ST) to read off the outside temperature.
Note! If the radiator is hot the outside temperature sensor will heat up if the car is stationary.
Is the outside temperature value within bounds?
Yes - VERIFIED
No - VERIFICATION FAILED
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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 - Exit fault-tracing
No - Attempt New Test
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Attempt New Test - Checking ground lead
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