Contents: General information ⇓ Troubleshooting Guide ⇓ Checking the Manifold Absolute…⇓ Checking the Intake Air Temperature…⇓ Checking the Intake Air Temperature…⇓
General information
The absolute pressure sensor in the intake manifold is a variable resistance sensitive to pressure changes. It detects the change in pressure in the intake manifold, which depends on the engine load and the crankshaft speed, and converts its value into a signal voltage (as the pressure decreases, the voltage drop of the sensor signal increases). The signal from the absolute pressure sensor is used by the electronic engine control unit to measure barometric pressure when starting the engine and under other certain conditions, which allows automatic adjustment of the operating parameters of the system at different altitudes above sea level.
The intake air temperature sensor, built into the manifold absolute pressure sensor, is a resistive type sensor that is sensitive to changes in air temperature.
Based on the sensor signals, the electronic engine control unit determines the required fuel supply (basic open time of the fuel injector) and the ignition timing.
- Nominal supply voltage of the sensor: 4.8-5.2 V
Troubleshooting Guide
Under the following conditions, the CHECK ENGINE indicator light comes on and the corresponding fault code is displayed:
- 1. If the intake manifold pressure is 11.8 kPa or lower for 0.1 second after the ignition is turned on.
- 2. If the intake manifold pressure is 11.8 kPa or lower when the engine is running at 1980 rpm or less.
- 3. If the intake manifold pressure is 98.6 kPa or higher and the engine is running at 2400 rpm or higher with the accelerator pedal released (for example, when the vehicle is moving downhill).
Checking the Manifold Absolute Pressure Sensor
1. Measure the voltage between terminals "1" (signal) and "4" (ground) of the connector on the sensor side under the specified conditions when the connector is connected.
- a) Check the voltage when the ignition switch is turned to the "ON" position and the engine is not running.
- Nominal value: 4-5V
- b) Check the voltage when the ignition switch is turned to the "ON" position and the engine is idling.
- Nominal value: 0.8-2.4V
- c) When the engine is idling, press the accelerator pedal sharply and check that the voltage increases from the nominal value.
- Nominal value: 0.8-2.4V
2. If the measured voltage differs from the nominal value, replace the manifold absolute pressure sensor.
Checking the Intake Air Temperature Sensor
1. Using a multimeter, measure the resistance between terminals "2" and "3" of the manifold absolute pressure sensor connector.
Table. Nominal values
| Air temperature | Nominal value |
| At 0°C | 3.3-3.7 Ohm |
| At 20°C | 2.4-2.8 Ohm |
| At 40°C | 1.6-2.0 Ohm |
| At 80°C | 0.5-0.9 Ohm |
2. If the measured resistance differs from the nominal value, replace the manifold absolute pressure sensor.
Checking the Intake Air Temperature Sensor with a Tester
1. Conditions for conducting the inspection.
Ignition switch: in the "ON" position or the engine is running.
2. Performing the check:
Read the tester readings (Intake Manifold Air Temperature).
Table. Nominal values.
| Engine condition | Nominal value |
| At -20°C | -20°C |
| At 0°C | 0°C |
| At 20°C | 20°C |
| At 40°C | 40°C |
| At 80°C | 80°C |
2. If the tester readings differ from the nominal value, replace the manifold absolute pressure sensor.