Component Location
P0102 Mass or Volume Air Flow Circuit Low Input
General Description (P0102)
Air mass flow sensor(AMS) is analog type sensor. AMS measures air quantity entering into the intake manifold as an electric voltage and relays the output voltage to the ECM. ECM performs EGR system feed back control with the information of measured mass air flow. (The role of AMS in diesel engine is different from gasoline engine. Fuel injection quantity is decided by MAFS signal in gasoline engine.)
When the amount of EGR gas(contains no oxygen) flowing into combustion chamber increases, the air passing through MAFS(contains oxygen) decreases. Thus, with the output signal change of AMS accompanied by EGR actuator actuation, ECM determines the amount of recirculated EGR gas quantity.
DTC Description (P0102)
If the output voltage of the air mass flow sensor is below 0.2V for 5.0 second or more, ECM judges this as a fault and DTC is set. The possible causes are short to ground, poor connection of connector, open in harness etc.
Fuel quantity and injection timing correction will not be controlled by ECM depending on operating change of EGR actuator but vehicle is possible to drive. In case of fail safe condition, ECM sets air quantity to 12.5g/s.
DTC Detecting Condition
| Item | Detecting Condition | Possible Cause | ||
| DTC Strategy | • Voltage monitoring |
•Poor connection of connector •Short to ground Open in harness
|
||
| Enable Conditions |
• Ignition ON/At driving | |||
| Threshold Value |
• Below 0.2V |
|||
| Diagnosis Time |
• Above 5.0 sec. |
|||
| Fail Safe | Fuel Cut | No | • 12.5g/s (default value) | |
| Fuel Limit | No | |||
| MIL | On | |||
Specification
1. Mass air flow sensor resistance
| Temperature(℃) | Resistance between terminal 1-2(kΩ) |
Resistance between terminal 1-3(kΩ) |
Resistance between terminal 2-3(kΩ) |
| 20 | 20.80 ± 10% | 22.72 ± 10% | 12.73 ± 10% |
Schematic Diagram
Monitor Scantool Data
1. Connect scantool to Data Link Connector(DLC).
2. Warm up the engine to normal operating temperature.
3. Turn the electrical equipment and air conditioner OFF.
4. Monitor “AMS” parameter on the scantool.
The value of “MAF air flow quantity” varies with the operation condition according to the DTC detecting condition. In case of fail safe, be sure to check that the value of “MAF air pressure quantity ” sets to 12.5g/s.
Fig.1) AMS data at ignition at idle
Fig.2) AMS data at 1000rpm
Fig.3) AMS data at 2000 rpm
Terminal & Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
| YES | Repair as necessary and then go to “Verification of Vehicle Repair” procedure. |
| NO | Go to “Signal Circuit Inspection” procedure. |
Signal Circuit Inspection
1. Signal Voltage Inspection
(1) Leave the AMS sensor connector connected.
(2) IG “On”, and set the start safety switch ON. Leave the engine “OFF”.
(3) Measure voltage between terminal 1 of AMS sensor harness connector and chassis ground.
Specification : Approx. 0.7V
The output voltage is varied according to air pressure.
(4) Is the voltage measured within specification?
| YES | Go to “Power Circuit Inspection” procedure. |
| NO | Go to “Signal Open Inspection” procedure. |
2. Signal Open Inspection
(1) IG “Off”, and set the start safety switch ON.
(2) Disconnect the AMS sensor connector and ECM connector.
(3) Measure resistance between terminal 1 of the AMS sensor harness connector and terminal 13 of ECM connector
Specification : Continuity(Below 1.0Ω)
(4) Is the resistance measured within specification?
| YES | Go to “Signal Short to Ground Inspection” procedure. |
| NO | Repair open in circuit and then go to “Verification of Vehicle Repair” procedure. |
3. Signal Short to Ground Inspection
(1) IG “OFF”, and set the start safety switch ON.
(2) Disconnect the AMS sensor connector and ECM connector.
(3) Measure resistance between terminal 1 of the AMS sensor harness connector and chassis ground.
Specification: Infinite
(4) Is the resistance measured within specification?
| YES | Go to “Component Inspection” procedure. |
| NO | Repair short to ground and then go to “Verification of Vehicle Repair” procedure. |
Power Circuit Inspection
1. Power Voltage Inspection
(1) Disconnect the AMS sensor connector.
(2) IG “On”, and set the start safety switch ON. Leave the engine “OFF”.
(3) Measure voltage between terminal 3 of the AMS sensor harness connector and chassis ground.
Specification: Approx. 14V
(4) Is the voltage measured within specification?
| YES | Go to “Component Inspection” procedure. |
| NO | Go to “Power Open Inspection” procedure. |
2. Power Open Inspection
(1) IG “OFF”, and set the start safety switch ON.
(2) Disconnect the AMS sensor connector and ECM connector.
(3) Measure resistance between terminal 3 of the AMS sensor harness connector and terminal 9 of ECM connector.
Specification : Continuity(Below 1.0Ω)
(4) Is the resistance measured within specification?
| YES | Go to “Power Short to Ground Inspection” procedure |
| NO | Repair open in circuit and then go to “Verification of Vehicle Repair” procedure |
3. Power Short to Ground Inspection
(1) IG “OFF”, and set the start safety switch ON.
(2) Disconnect the AMS sensor connector and ECM connector.
(3) Measure resistance between terminal 3 of the AMS sensor harness connector and chassis ground.
Specification : Infinite
| YES | Go to “Component Inspection” procedure. |
| NO | Repair short to ground and then go to “Verification of Vehicle Repair” procedure. |
Component Inspection
1. AMS Sensor Resistance Inspection
(1) IG “Off”, and set the start safety switch ON.
(2) Disconnect the AMS sensor connector.
(3) Measure resistance between terminals 1-2, 1-3 and 2-3 of AMS sensor.
Specification
| Temperature (℃) | Resistance between terminal 1-2(kΩ) |
Resistance between terminal 1-3(kΩ) |
Resistance between terminal 2-3(kΩ) |
| 20 | 20.80 ± 10% | 22.72 ± 10% | 12.73 ± 10% |
(4) Is the resistance measured within specification?
| YES | Go to “Verification of Vehicle Repair” procedure. |
| NO | Replace the AMS sensor and then go to “Verification of Vehicle Repair” procedure. |
Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select “Diagnostic Trouble Codes(DTCs)” mode.
2. Using a scantool, clear the DTC.
3. Operate the vehicle within DTC enable conditions in General Information.
4. Are any DTCs present?
| YES | Go to the applicable DTC procedure. |
| NO | System is performing to specification at this time. |
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