P1401

Reference Data:

Component Description
The EGR temperature sensor detects temperature changes in the EGR passage way. When the EGR valve opens, hot exhaust gases flow, and the temperature in the passage way changes. The EGR temperature sensor is a thermistor that modifies a voltage signal sent from the ECM. This modified signal then returns to the ECM as an input signal. As the temperature increases, EGR temperature sensor resistance decreases.

This sensor is not used to control the engine system. It is used only for the on board diagnosis.

On Board Diagnosis Logic:

DTC Confirmation Procedure
Perform "PROCEDURE FOR MALFUNCTION A" first. If 1st trip DTC cannot be confirmed, perform "PROCEDURE FOR MALFUNCTION B".

NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.

PROCEDURE FOR MALFUNCTION A

With CONSULT
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT.
3. Verify that "COOLAN TEMP/S" is less than 40°C (104°F).
If the engine coolant temperature is above the range, cool the engine down.

4. Start engine and let it idle for at least 8 seconds.
5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
1. Turn ignition switch "ON".
2. Select "MODE 1" with GST.
3. Verify that engine coolant temperature is less than 40°C (104°F).
If the engine coolant temperature is above the range, cool the engine down.
4. Start engine and let it idle for at least 8 seconds.
5. Select "MODE 7" with GST.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

Without Scan Tool
1. Turn ignition switch "ON".
2. Verify that voltage between ECM terminal 59 (engine coolant temperature sensor signal) is more 2.7V.
If the voltage is below the range, cool the engine down.
3. Start engine and let it idle for at least 8 seconds.

4. Turn ignition switch "OFF" and wait at least 5 seconds.
5. Turn ignition switch "ON" and perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

PROCEDURE FOR MALFUNCTION B

CAUTION: Always drive vehicle at a safe speed.

TESTING CONDITION:
Always perform the test at a temperature of 5°C (41 °F) or higher.

With CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Confirm that EGR valve is not lifting at idle.
If the check result is NG, go to trouble diagnoses for "DTC P1402".
3. Select "DATA MONITOR" mode with CONSULT.
4. Read "EGR TEMP SEN" at about 1,500 rpm while holding the EGR valve in full open position by hand.
Voltage should decrease to less than 1.5V.
If the check result is NG, go to "Diagnostic Procedure" below.
If the check result is OK, go to following step.
5. Turn ignition switch "OFF" and wait at least 5 seconds.
6. Turn ignition switch "ON".
7. Check the output voltage of "THRTL POS SEN" at closed throttle position and note it.
8. Start engine.
9. Maintain the following conditions for at least 5 consecutive seconds.

CMPS.RPM (REF) 1,600 - 2,400 rpm (A/T)
1,800 - 2,600 rpm (M/T)
COOLAN TEMP/S Above 80°C (176°F)
B/FUEL SCHDL 3.0 - 4.5 msec
THRTL POS SEN X - (X + 0.70) V
X = Voltage value measured at step 8
Selector lever Suitable position

10. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

Overall Function Check
Use this procedure to check the overall function of the EGR temperature sensor. During this check, a 1st trip DTC might not be confirmed.

PROCEDURE FOR MALFUNCTION B

Without CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Confirm that EGR valve is not lifting at idle. If NG, go to trouble diagnoses for DTC P0400 and P0402.
3. Check voltage between ECM terminal 63 (EGR temperature sensor signal) and ground at about 1,500 rpm with EGR valve lifted up to the full position by hand.
Voltage should decrease to less than 1.5V.
If NG, go to "Diagnostic Procedure" below.
4. If step 4 is OK, perform trouble diagnoses for "DTC P0400, P1400".