Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71-, Checking

Function

Air mass and charge pressure are two factors used for engine load management. For this purpose, there are several sensors with absolutely identical functions. They measure the intake air temperature and the intake manifold pressure. The first sender unit is located upstream of the throttle valve control module J338 and contains the following senders:

- Intake Air Temperature Sensor -G42-.
- Manifold Absolute Pressure Sensor -G71-.

They measure the pressure and temperature of the air in each individual cylinder bank. The values measured here correspond to the actual air mass in the cylinder bank(s).

Note the Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- is also known as the Intake Manifold Sensor -GX9-.

Special tools and workshop equipment required

Multimeter.
Wiring Diagram.
Scan Tool.

Test requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with Auto. Transmission, ensure Selector Lever position is in "P".
Vehicles with Man. Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .
For Hybrid vehicles refer to: HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	YES: GO TO Step 2. NO: GATHER more information from customer about the complaint.
2	DISCONNECT: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- harness connector. IGNITION: ON. CHECK: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- harness connector terminals 1 to 3 for voltage. SPECIFIED VALUE: About 5.0 V. IGNITION: OFF. -- Was Value obtained?	YES: GO TO Step 3. NO: GO TO Step 4.
3	REMOVE: Engine Control Module - J623-. Refer to appropriate Service Information. CHECK: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- harness connector terminal 2 to the Engine Control Module - J623- harness connector T94 / 21 for resistance. CHECK: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- harness connector terminal 4 to the Engine Control Module - J623- harness connector T94 / 24 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω) -- Were Values obtained?	YES: REPLACE: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71-. Refer to appropriate Service Information. GO TO: Step 5. NO: CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5.
4	REMOVE: Engine Control Module - J623-. Refer to appropriate Service Information. CHECK: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- harness connector terminal 1 to the Engine Control Module - J623- harness connector T60 / 14 for resistance. CHECK: Intake Air Temperature Sensor -G42- / Manifold Absolute Pressure Sensor -G71- harness connector terminal 3 to the Engine Control Module - J623- harness connector T60 / 37 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	YES: REPLACE Engine Control Module -J623- Refer to appropriate Service Information. GO TO: Step 5. NO: CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 5.
5	Final Procedure Perform a road test to verify repair. Do any DTC's return:	YES: Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY . Perform the diagnostic procedure for that DTC. NO: Repair is complete. Generate readiness code. Refer to READINESS CODE . Return vehicle to Customer.