• P0100       Mass or Volume Air flow Circuit Malfunction
  • P0101       Mass or Volume Air flow Circuit Range/Performance Problem
  • P0102       Mass or Volume Air Flow Circuit low Input
  • P0103       Mass or Volume Air flow Circuit High Input
  • P0104       Mass or Volume Air flow Circuit Intermittent
  • P0105       Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
  • P0106       Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
  • P0107       Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
  • P0108       Manifold Absolute Pressure/Barometric Pressure Circuit High Input
  • P0109       Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
  • P0110       Intake Air Temperature Circuit Malfunction
  • P0111       Intake Air Temperature Circuit Range/Performance Problem
  • P0112       Intake Air Temperature Circuit Low Input
  • P0113       Intake Air Temperature Circuit High Input
  • P0114       Intake Air Temperature Circuit Intermittent

These can be set if the coolant sensor readings do not change as the engine warms up, if the readings are too high or too low (out of range), if there is no signal from the sensor, or if the engine overheats. The coolant sensor monitors engine temperature. This is a key function because it allows the fuel management system to go into the closed loop mode of operation when the engine warms up. The computer also uses engine temperature to control other functions, too. A failure here can prevent the system from going into closed loop causing a rich fuel mixture, and an increase in fuel consumption and emissions. A coolant sensor’s resistance changes as the temperature increases. If you don’t see a change in the resistance as the engine warms up, or the resistance is out of specifications, the sensor is bad. Other things that can cause bad sensor readings include a low coolant level in the cooling system, a thermostat that is stuck open or shut, or a thermostat that has the wrong temperature rating for the engine. CAUTION: Do not open the radiator cap if the coolant is hot! Wait until the engine and radiator have cooled to open the cap.

  • P0115       Engine Coolant Temperature Circuit Malfunction
  • P0116       Engine Coolant Temperature Circuit Range/Performance Problem
  • P0117       Engine Coolant Temperature Circuit Low Input
  • P0118       Engine Coolant Temperature Circuit High Input
  • P0119       Engine Coolant Temperature Circuit Intermittent

These can be set if the TPS readings are too high or too low (out of range), if the signal is lost, or if the signal does not correspond to the MAP sensor’s readings. The TPS sensor monitors the position of the throttle so the computer can add more fuel when the engine is accelerating or under load. The computer may also need to know when the throttle is at idle or wide open to control other functions. A bad TPS can cause driveability problems such as hesitation. The sensor’s resistance changes as the throttle moves, causing the return voltage signal to vary. Look for a change in the voltage output as the throttle opens and closes. No change or skips in the output would indicate a faulty TPS sensor. Also note: the idle voltage is adjustable on some TPS sensors and must be set within specifications for accurate operation. If the voltage adjustment is not within specifications, it can adversely affect performance and throttle response.

  • P0120       Throttle Pedal Position Sensor/Switch A Circuit Malfunction
  • P0121       Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem
  • P0122       Throttle/Pedal Position Sensor/Switch A Circuit Low Input
  • P0123       Throttle/Pedal Position Sensor/Switch A Circuit High Input
  • P0124       Throttle/Pedal Position Sensor/Switch A Circuit Intermittent
  • P0125       Insufficient Coolant Temperature for Closed Loop Fuel Control
  • P0126       Insufficient Coolant Temperature for Stable Operation

These can be set if the O2 sensor readings remain low (lean), or high (rich), or do not change quickly enough, or do not change at all. The O2 sensor reads unburned oxygen in the exhaust, and generates a voltage signal that is proportional to the amount of oxygen in the exhaust. The signal can vary from a low of about 0.1 volts up to a high of about 0.9 volts. A low voltage signal indicates a lean fuel mixture. A high voltage signal indicates a rich fuel mixture. The engine computer uses the O2 sensor’s input to balance the fuel mixture during closed loop operation. A bad sensor may prevent the system from going into closed loop, and usually causes the fuel mixture to run rich causing an increase in fuel consumption and emissions. A low voltage (lean) reading may indicate a bad O2 sensor, a vacuum leak, or a condition that allows unburned oxygen to
enter the exhaust. Check intake vacuum at idle, and inspect vacuum hose connections. If okay, check for a misfiring cylinder, a burned exhaust valve that is leaking compression, or a leaky exhaust manifold gasket. O2 sensor quick checks include watching the sensor’s output voltage as the fuel mixture changes. Momentarily disconnecting a vacuum hose will cause a lean response from the O2 sensor. No change in the reading or a very sluggish response would indicate a bad O2 sensor. NOTE: If you get an oxygen sensor code plus a random misfire code and a MAP sensor code, the engine probably has a serious vacuum leak.

  • P0130       O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
  • P0131       O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
  • P0132       O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
  • P0133       O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
  • P0134       O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
  • P0135       O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
  • P0136       O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
  • P0137       O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
  • P0138       O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
  • P0139       O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
  • P0140       O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
  • P0141       O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
  • P0142       O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)
  • P0143       O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
  • P0144       O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)
  • P0145       O2 Sensor Circuit Slow Response (Bank 1 Sensor 3)
  • P0146       O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)
  • P0147       O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
  • P0150       O2 Sensor Circuit Malfunction (Bank 2 Sensor 1)
  • P0151       O2 Sensor Circuit Low Voltage (Bank 2 Sensor 1)
  • P0152       O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)
  • P0153       O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)
  • P0154       O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
  • P0155       O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
  • P0156       O2 Sensor Circuit Malfunction (Bank 2 Sensor 2)
  • P0157       O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
  • P0158       O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
  • P0159       O2 Sensor Circuit Slow Response (Bank 2 Sensor 2)
  • P0160       O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
  • P0161       O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
  • P0162       O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)
  • P0163       O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
  • P0164       O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)
  • P0165       O2 Sensor Circuit Slow Response (Bank 2 Sensor 3)
  • P0166       O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)
  • P0167       O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)
  • P0170       Fuel Trim Malfunction (Bank 1)
  • P0171       System Too Lean (Bank 1)
  • P0172       System Too Rich (Bank 1)
  • P0173       Fuel Trim Malfunction (Bank 2)
  • P0174       System Too Lean (Bank 2)
  • P0175       System Too Rich (Bank 2)
  • P0176       Fuel Composition Sensor Circuit Malfunction
  • P0177       Fuel Composition Sensor Circuit Range/Performance
  • P0178       Fuel Composition Sensor Circuit Low Input
  • P0179       Fuel Composition Sensor Circuit High Input
  • P0180       Fuel Temperature Sensor A Circuit Malfunction
  • P0181       Fuel Temperature Sensor A Circuit Performance
  • P0182       Fuel Temperature Sensor A Circuit low Input
  • P0183       Fuel Temperature Sensor A Circuit High Input
  • P0184       Fuel Temperature Sensor A Circuit Intermittent
  • P0185       Fuel Temperature Sensor B Circuit Malfunction
  • P0186       Fuel Temperature Sensor B Circuit Range/Performance
  • P0187       Fuel Temperature Sensor U Circuit Low Input
  • P0188       Fuel Temperature Sensor B Circuit High Input
  • P0189       Fuel Temperature Sensor B Circuit Intermittent
  • P0190       Fuel Rail Pressure Sensor Circuit Malfunction
  • P0191       Fuel Rail Pressure Sensor Circuit Range/Performance
  • P0192       Fuel Rail Pressure Sensor Circuit Low Input
  • P0193       Fuel Rail Pressure Sensor Circuit High Input
  • P0194       Fuel Rail Pressure Sensor Circuit Intermittent
  • P0195       Engine Oil Temperature Sensor Malfunction
  • P0196       Engine Oil Temperature Sensor Range/Performance
  • P0197       Engine Oil Temperature Sensor Low
  • P0198       Engine Oil Temperature Sensor High
  • P0199       Engine Oil Temperature Sensor Intermittent