P1100
MAF Intermittant (Mazda)
P1101
MAF Out Of Range (Mazda)
P1106
Manifold Absolute Pressure (MAP) sensor circuit intermittent high voltage
P1107
Manifold Absolute Pressure (MAP) sensor circuit intermittent low voltage
P1108
BARO to MAP signal circuit comparison too high
P1111
Intake Air Temperature (IAT) sensor intermittent high voltage
P1112
Intake Air Temperature (IAT) sensor intermittent low voltage
P1114
Engine Coolant Temperature (ECT) sensor circuit intermittent low voltage
P1115
Engine Coolant Temperature (ECT) sensor circuit intermittent high voltage
P1115
Intake Air Temperature 2 Circuit High Input (Ford)
P1116
ECT Sensor Out Of Range (Mazda)
P1116
ECT Sensor Out Of Range (Ford)
P1117
ECT Intermittent (Mazda)
P1117
ECT Intermittent (Ford)
P1120
TPS Out Of Range Low (Mazda)
P1120
TPS Out Of Range Low (Ford)
P1121
Throttle Position (TP) Sensor Inconsistent With MAF Sensor High Voltage
P1122
Throttle Position (TP) Sensor Inconsistent With MAF Sensor Low Voltage
P1124
TPS Out Of Self Teat Range (Mazda)
P1124
TPS Out Of Self Teat Range (Ford)
P1125
TPS Intermittant (Mazda)
P1125
TPS Intermittant (Ford)
P1127
Exhaust Not Warm Enough, Downstream Sensor Not Tested (Ford)
P1128
MAP Lower Than Expected (Acura)
P1129
Upstream O2 Sensors Swapped Bank To Bank (HO2S-11-21) (Ford)
P1129
MAP Higher Than Expected (Acura)
P1129
Downstream O2 Sensors Swapped Bank To Bank (HO2S-12-22) (Ford)
P1130
Heated O2 Sensor (HO2S) 11 At Adaptive Limit (Mazda)
P1130
Lack Of HO2S-11, Fuel Trim At Limit (Ford)
P1131
HO2S 11 Indicates Lean (Mazda)
P1131
HO2S 11 Indicates Lean (Ford)
P1132
HO2S 11 Indicates Rich (Mazda)
P1132
HO2S 11 Indicates Rich (Ford)
P1133
Heated Oxygen Sensor (HO2S) insufficient switching bank 1 sensor 1 (Rear Bank)
P1134
Heated Oxygen Sensor (HO2S) transition time ratio bank 1 sensor 1 (Rear Bank)
P1137
Lack Of HO2S-12 Switch Indicates Lean (Ford)
P1138
Lack Of HO2S-12 Switch Indicates Rich (Ford)
P1150
Lack Of HO2S-21 Switch Fuel Trim At Limit (Ford)
P1151
Lack Of HO2S-21 Switch Indicates Lean (Ford)
P1152
Lack Of HO2S-21 Switch Indicates Rich (Ford)
P1153
Heated Oxygen Sensor (HO2S) insufficient switching bank 2 sensor 1 (Front Bank)
P1154
Heated Oxygen Sensor (HO2S) transition time ratio bank 2 sensor 1 (Front Bank)
P1157
Lack Of HO2S-22 Switch Indicates Lean (Ford)
P1158
Lack Of HO2S-22 Switch Indicates Rich (Ford)
P1168
FRP Sensor In Range But Low (Ford)
P1169
FRP Sensor In Range But High (Ford)
P1180
Fuel Delivery System Low (Ford)
P1181
Fuel Delivery System High (Ford)
P1183
EOT Sensor Circuit Malfunction (Ford)
P1184
EOT Sensor Out Of Range (Ford)
P1189
Engine Oil Pressure Switch Circuit
P1192
Inlet Air Temp. Circuit Low (Chrysler)
P1193
Inlet Air Temp. Circuit High (Chrysler)
P1195
1/1 O2 Sensor Slow During Catalyst Monitor (Chrysler)
P1196
2/1 O2 Sensor Slow During Catalyst Monitor (Chrysler)
P1197
1/2 O2 Sensor Slow During Catalyst Monitor (Chrysler)
P1198
Radiator Temperature Sensor Volts Too High (Chrysler)
P1199
Radiator Temperature Sensor Volts Too Low (Chrysler)
System Too Lean – Bank 1
Description:
How does a P0171 code trigger the check engine light? This code will trigger the check engine light as follows:
The adaptive fuel strategy in the vehicle’s computer constantly monitors the fuel delivery system to make sure the engine is running at an optimum air to fuel ratio, which is 14.7:1. The computer adjusts injector pulse width to regulate the amount of fuel going into the engine. The oxygen sensors relay information to the Powertrain Control Module (computer), informing it of the oxygen content in the exhaust. This information is translated by the computer, and used to determine if more or less fuel is needed. The computer will then adjust fuel flow (and possibly other related engine operating characteristics), to keep the correct air fuel mixture. This loop continues as long as the engine is running. Please refer to our article Oxygen Sensor Code Diagnosis for more info on this system. A P0171 check engine light code is set when the computer has reached a rich calibration limit and can not add enough fuel to maintain the correct mixture.
Possible Causes:
Refer to our Oxygen Sensor Code Diagnosis article for a list of all possible causes. The following is an overview of P0171 check engine light code possible causes.
Fuel System:
Leaking or faulty fuel pressure regulator
Plugged or dirty fuel filter or lines
Fuel pump weak or defective check valve
Injectors leaking or faulty
Low fuel pressure or running out of fuel
Leaking EVAP system components
Faulty FRP (Fuel Rail Pressure Sensor)
Air Intake System
Vacuum leaks
Contaminated, damaged or faulty Mass Air Flow sensor
PCV valve leak or stuck open
Air induction turbulance caused by wrong filter
Oil dipstick not seated
Air leaks after the Mass Air Flow Sensor (MAF)
Oil coated aftermarket air filter
Exhaust System
Any exhaust leak before or near the oxygen sensors
EGR System
Vacuum line disconnected from EGR System Module (ESM)
EGR valve, tube or gasket leak
EGR vacuum regulator valve leaking
Secondary Air Injection System
Mechanically stuck secondary air injection valve
Mass Air Flow (MAF) Circuit Low Input
Description:
How does a P0102 code trigger the check engine light? The engine light will come on if the following concern is present:
The Mass Air Flow Sensor circuit is monitored by the powertrain control module (computer), for low voltage (which translates to low air flow) through the Comprehensive Component Monitor (CCM). With the key on and engine running, if the voltage drops below a minimum value this code will be set, causing the check engine light to illuminate.
Possible Causes:
MAF Sensor disconnected
MAF Sensor circuit open to computer
Vehicle Power circuit open to MAF Sensor
Power Ground circuit open to MAF Sensor
MAF Sensor Return circuit open to PCM
MAF Sensor circuit shorted to Ground
Intake air leak near MAF Sensor
Damaged MAF Sensor
Damaged computer
Diagnostic Help:
Refer to an appropriate manual for specification. If MAF Sensor voltage reading is below minimum limit with key on engine running then concern is a hard fault (present now). If all values are in spec proceed with intermittent diagnosis (refer to our “Intermittent Diagnosis Help” article through the “articles” link on the Navigation Bar). You may also use the “Get Help” link if you need specifications or have any other related questions.
Mass Air Flow (MAF) Sensor
Description:
How does a P0100 code trigger the check engine light? This code will trigger the check engine light under the following conditions:
1. The computer receives an excessively high voltage from the MAF Sensor with the engine not running.
2. The computer receives an excessively low voltage from the MAF Sensor with the engine running.
3. The computer receives a high voltage reading from the MAF Sensor under light-load driving conditions.
Possible Causes:
MAF Sensor circuit open or shorted
Intake air leaks (unmetered air after MAF Sensor)
Defective MAF Sensor
Electronic Control Module (ECM)/Powertrian Control Module (PCM) concern
Diagnostic Help:
Monitor MAF Sensor voltage reading while increasing engine RPM. The MAF Sensor value should increase in proportion to engine speed. If not, first check for air leaks at intake tube, manifold and all vacuum lines. Then test the MAF Sensor circuits for opens and shorts. See our article Automotive Circuit Testing 101, if you need more assistance with this. If concern is determined to be intermittent, wiggle test connectors and wiring to attempt to duplicate concern. You may also use the “Get Help” link if you need specifications or have any other related questions. Remember to refer to an appropriate manual for specific instruction.