Pontiac Fiero 1988 Service Manual page 496

DRIVEABILITY A N D EMISSIONS - F U E L INJECTION (TBI) 6E2-A-41
CODE 25
MANIFOLD AIR TEMPERATURE (MAT)
SENSOR CIRCUIT
( H I G H T E M P E R A T U R E INDICATED)
2.5L "P" SERIES (TBI)
©
DOES "SCAN" TOOL DISPLAY MAT 145°C OR HOTTER?
YES
DISCONNECT SENSOR.
"SCAN" SHOULD DISPLAY TEMPERATURE
BELOW -30°C
DOES IT?
YES
FAULTY SENSOR
DIAGNOSTIC AID
MAT SENSOR
TEMPERATURE TO RESISTANCE VALUES
(APPROXIMATE]
°F °C OHMS
210 100
185
160 70 450
100 38
1,800
70 20 3,400
40
4
7,500
20 -7 13,500
0 -18 25,000
-40 -40 100,700
NO
CODE 25 IS INTERMITTENT.
IF NO ADDITIONAL CODES WERE
STORED, REFER TO "DIAGNOSTIC
AIDS" ON FACING PAGE
NO
CKT 472 SHORTED TO GROUND.
OR
CKT 472 SHORTED TO SENSOR GROUND CIRCUIT.
OR
fAULTY ECM.
CLEAR CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NO "SERVICE ENGINE SOON" LIGHT.
4-28-87
• 7S3190-6E