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DTC P0100 Mass or Volume Air Flow Circuit DTC P0102 Mass or Volume Air Flow Circuit Low Input DTC P0103 Mass or Volume Air Flow Circuit High Input

The document summarizes diagnostics for the mass air flow sensor circuit in a 2004 Toyota Corolla. It lists three diagnostic trouble codes - P0100 for a circuit issue, P0102 for a low input, and P0103 for a high input. It describes how the mass air flow sensor works by measuring air flow through a heated platinum wire and thermister. The circuit maintains a constant temperature difference between the wire and thermister to determine air flow based on voltage output. Next steps are to confirm the specific trouble code and check the mass air flow ratio using a diagnostic tool.

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Clodoaldo Biassio
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503 views1 page

DTC P0100 Mass or Volume Air Flow Circuit DTC P0102 Mass or Volume Air Flow Circuit Low Input DTC P0103 Mass or Volume Air Flow Circuit High Input

The document summarizes diagnostics for the mass air flow sensor circuit in a 2004 Toyota Corolla. It lists three diagnostic trouble codes - P0100 for a circuit issue, P0102 for a low input, and P0103 for a high input. It describes how the mass air flow sensor works by measuring air flow through a heated platinum wire and thermister. The circuit maintains a constant temperature difference between the wire and thermister to determine air flow based on voltage output. Next steps are to confirm the specific trouble code and check the mass air flow ratio using a diagnostic tool.

Uploaded by

Clodoaldo Biassio
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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05–65

DIAGNOSTICS – SFI SYSTEM (April, 2003) 059VF–08

DTC P0100 MASS OR VOLUME AIR FLOW CIRCUIT

DTC P0102 MASS OR VOLUME AIR FLOW CIRCUIT


LOW INPUT

DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT


HIGH INPUT

CIRCUIT DESCRIPTION
The MAF (Mass Air Flow) sensor measures the amount of air flowing through the throttle valve. The ECM
uses this information to determine the fuel injection time and provide a proper air–fuel ratio. Inside the MAF
sensor, there is a heated platinum wire exposed to the flow of intake air.
By applying a specific current to the wire, the ECM heats this wire to a given temperature. The flow of incom-
ing air cools the wire and an internal thermister, changing their resistance. To maintain a constant current
value, the ECM varies the voltage applied to these components in the MAF sensor. The voltage level is pro-
portional to the airflow through the sensor and the ECM interprets this voltage as the intake air amount.
The circuit is constructed so that the platinum hot wire and the temperature sensor provides a bridge circuit,
with the power transistor controlled so that the potential of A and B remains equal to maintain the set temper-
ature.

B+
Temperature sensor
Power Transistor
Platinum Hot Wire
(Heater)

A B Output
Voltage Temperature
sensor
Platinum Hot Wire (Heater)

A80089

DTC No. DTC Detection Condition Trouble Area


When the mass air flow sensor circuit has an open or short for
P0100
more than 3 seconds.
 Open
O or short
h t in
i mass air
i flow
fl sensor circuit
i it
When the mass air flow sensor circuit has an open for more
P0102  Mass air flow sensor
than 3 seconds.
 ECM
When the mass air flow sensor circuit has a short for more
P0103
than 3 seconds.

HINT:
After confirming DTC P0100, P0102 or P0103, confirm the mass air flow ratio in the ”DIAGNOSIS / EN-
HANCED OBD II / DATA LIST / ALL” using the hand–held tester or the OBD II scan tool.

2004 COROLLA (RM1037U)

Author: Date: 230

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