Toyota Celica 2005 Repair Manual page 276

DTC P0101
CIRCUIT DESCRIPTION
Refer to DTC P0100 on page DI−71.
DTC No.
S High voltage:
Conditions (a), (b) and (c) continue for more than 10 seconds
(2 trip detection logic):
(a) Engine speed less than 2,000 rpm
(b) Engine coolant temperature 70°C (158°F) or higher
(c) Voltage output of Mass Air Flow (MAF) meter more than 2.2
P0101 V (varies with Throttle Position [TP] sensor voltage)
S Low voltage:
Conditions (a) and (b) continue for more than 10 seconds
(2 trip detection logic):
(a) Engine speed more than 300 rpm
(b) Voltage output of MAF meter less than 0.93 V
(varies with TP sensor voltage)
MONITOR DESCRIPTION
The MAF (Mass Air Flow) meter helps the ECM calculate 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 meter, 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 incoming air cools the wire and an
internal thermistor, changing their resistance. To maintain a constant current value, the ECM varies the volt-
age applied to these components in the MAF meter. The voltage level is proportional to the air flow through
the MAF meter. The ECM interprets this voltage as the intake air amount. If there is a defect in the MAF meter
or an open or short circuit, the voltage level will deviate from the normal operating range. The ECM interprets
this deviation as a defect in the MAF meter and sets a DTC.
Example:
If the voltage is more than 2.2 V with idling or less than 0.4 V without idling, the ECM interprets this as a defect
in the MAF meter and sets a DTC.
MONITOR STRATEGY
Related DTCs
Required sensors/components
Frequency of operation
Duration
MIL operation
Sequence of operation
2005 CELICA (RM1131U)
DIAGNOSTICS
Mass Air Flow Circuit Range/Performance
Problem
DTC Detecting Condition
Main sensors/components
Related sensors/components
Continuous
10 sec. (High voltage)
6 sec. (Low voltage)
2 driving cycles
None
− ENGINE (1ZZ−FE)
S Mass air flow meter
P0101
275
Trouble Area
Mass air flow meter rationality
Mass air flow meter
Engine speed sensor, Engine coolant tempera-
ture sensor, Throttle position sensor
DI−77
DI09C−27