Based on information from various sensors, the PCM measures the fuel injection amount. The fuel injector is a solenoid-operated valve and the fuel injection amount is controlled by length of time the fuel injector is held open. The PCM controls each injector by grounding the control circuit. When the PCM energizes the injector by grounding the control circuit, the circuit voltage should be low (theoretically 0V) and the fuel is injected. When the PCM de-energizes the injector by opening control circuit, the fuel injector is closed and circuit voltage should momentarily peak.
PCM sets DTC P0271 if the PCM detects that injector (Cylinder #4) control circuit is open or shorted to battery voltage.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Driver Stage Check
? Open or short to battery in control harness
? Contact resistance in connectors
? Faulty injector
Enable Conditions
? 10 = Battery voltage(V) =16
? Engine speed(rpm) >30
Threshold Value
? Open or short to battery
Diagnostic Time
? 1.5 sec.
Temp.(?)
Resistance (O)
-20
-4
12.2 ~ 12.3
40
104
15.5 ~ 15.7
-10
14
12.9 ~ 13.1
50
122
16.1 ~ 16.3
0
32
13.3 ~ 13.5
60
140
16.6 ~ 16.8
10
13.9 ~ 14.0
80
176
17.7 ~ 17.9
20
68
14.4 ~ 14.6
100
212
18.8 ~ 19.0
30
86
15.0 ~ 15.2
120
248
19.9 ~ 20.1