On Board Diagnosis Logic
NBEC0053
Malfunction is detected when
(Malfunction A) an excessively high voltage from the sensor is
sent to ECM when engine is not running,
(Malfunction B) an excessively low voltage from the sensor is sent
to ECM when engine is running,
(Malfunction C) a high voltage from the sensor is sent to ECM
under light load driving condition,
(Malfunction D) a low voltage from the sensor is sent to ECM
under heavy load driving condition,
(Malfunction E) a voltage from the sensor is constantly approx.
1.0V when engine is running.
FAIL-SAFE MODE
NBEC0053S02
When the malfunction B is detected, the ECM enters fail-safe mode
and the MIL lights up.
Detected items
Engine operating condition in fail-safe mode
Mass air flow sensor circuit
Engine speed will not rise more than 2,400 rpm due to the fuel cut.
Possible Cause
NBEC0426
MALFUNCTION A OR C
NBEC0426S01
I
Harness or connectors
(The sensor circuit is open or shorted.)
I
Mass air flow sensor
MALFUNCTION B, D OR E
NBEC0426S02
I
Harness or connectors
(The sensor circuit is open or shorted.)
I
Intake air leaks
I
Mass air flow sensor
DTC Confirmation Procedure
NBEC0054
Perform “PROCEDURE FOR MALFUNCTION A” first.
If the 1st trip DTC cannot be confirmed, perform “PROCE-
DURE FOR MALFUNCTION B AND E”.
If there is no problem on “PROCEDURE FOR MALFUNCTION
B AND E”, perform “PROCEDURE FOR MALFUNCTION C”.
If there is no problem on “PROCEDURE FOR MALFUNCTION
C”, perform “PROCEDURE FOR MALFUNCTION D”.
NOTE:
If “DTC Confirmation Procedure” has been previously conducted,
always turn ignition switch “OFF” and wait at least 10 seconds
before conducting the next test.
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0100 MASS AIR FLOW SENSOR (MAFS)
On Board Diagnosis Logic
EC-151