P0100-P0199 – Fuel and Air Metering. OBD-II

  • P0100 Mass or Volume Air Flow “A” Circuit Malfunction
  • P0101 Mass or Volume Air Flow “A” Circuit Range/Performance Problem
  • P0102 Mass or Volume Air Flow “A” Circuit Low Input
  • P0103 Mass or Volume Air Flow “A” Circuit High Input
  • P0104 Mass or Volume Air Flow “A” Circuit Intermittent
  • Some trouble codes that may come up related to MAP sensors: P0105, P0106, P0107, P0108, P0109
  • 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
  • P010A Mass or Volume Air Flow “B” Circuit
  • P010B Mass or Volume Air Flow “B” Circuit Range/Performance
  • P010C Mass or Volume Air Flow “B” Circuit Low
  • P010D Mass or Volume Air Flow “B” Circuit High
  • P010E Mass or Volume Air Flow “B” Circuit Intermittent/Erratic
  • P010F Mass or Volume Air Flow Sensor A/B Correlation
  • P0110 Intake Air Temperature Circuit Malfunction Bank 1
  • P0111 Intake Air Temperature Circuit Range/Performance Problem Bank 1
  • P0112 Intake Air Temperature Circuit Low Input Bank 1
  • P0113 Intake Air Temperature Circuit High Input Bank 1
  • P0114 Intake Air Temperature Circuit Intermittent Bank 1
  • If the ECT sensor or associated wiring has failed, you may see some of the following ECT sensor DTC trouble codes: P0115 – P0116 – P0117 – P0118 – P0119 – P0125 – P0126 – P0127 – P0128
  • P0115 Engine Coolant Temperature Sensor Circuit 1 Malfunction
  • P0116 Engine Coolant Temperature Sensor Circuit 1 Range/Performance Problem
  • P0117 Engine Coolant Temperature Sensor Circuit 1 Low Input
  • P0118 Engine Coolant Temperature Sensor Circuit 1 High Input
  • P0119 Engine Coolant Temperature Sensor Circuit 1 Intermittent
  • P011A Engine Coolant Temperature Sensor 1/2 Correlation
  • P011B Engine Coolant Temperature/Intake Air Temperature Correlation
  • P011C Charge Air Temperature/Intake Air Temperature Correlation Bank 1
  • P011D Charge Air Temperature/Intake Air Temperature Correlation Bank 2
  • P0120 Throttle Position Sensor/Switch A Circuit Malfunction
  • P0121 Throttle Position Sensor/Switch A Circuit Range/Performance Problem
  • P0122 Throttle Position Sensor/Switch A Circuit Low Input
  • P0123 Throttle Position Sensor/Switch A Circuit High Input
  • P0124 Throttle Position Sensor/Switch A Circuit Intermittent
  • P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control
  • P0126 Insufficient Coolant Temperature for Stable Operation
  • P0127 Intake Air Temperature Too High
  • P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
  • P0129 Barometric Pressure Too Low
  • P012A Turbocharger/Supercharger Inlet Pressure Sensor Circuit (Downstream of throttle valve)
  • P012B Turbocharger/Supercharger Inlet Pressure Sensor Circuit Range/Performance (Downstream of throttle valve)
  • P012C Turbocharger/Supercharger Inlet Pressure Sensor Circuit Low (Downstream of throttle valve)
  • P012D Turbocharger/Supercharger Inlet Pressure Sensor Circuit High (Downstream of throttle valve)
  • P012E Turbocharger/Supercharger Inlet Pressure Sensor Circuit Intermittent/Erratic (Downstream of throttle valve)
  • P0130 02 Sensor Circuit Malfunction (Bank I Sensor 1)
  • P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
  • P0132 02 Sensor Circuit High Voltage (Bank I Sensor 1)
  • P0133 02 Sensor Circuit Slow Response (Bank 1 Sensor 1)
  • P0134 02 Sensor Circuit No Activity Detected (Bank I Sensor 1)
  • P0135 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
  • P0136 02 Sensor Circuit Malfunction (Bank I Sensor 2)
  • P0137 02 Sensor Circuit Low Voltage (Bank I Sensor 2)
  • P0138 02 Sensor Circuit High Voltage (Bank I Sensor 2)
  • P0139 02 Sensor Circuit Slow Response (Bank 1 Sensor 2)
  • P013A O2 Sensor Slow Response – Rich to Lean (Bank 1 Sensor 2)
  • P013B O2 Sensor Slow Response – Lean to Rich (Bank 1 Sensor 2)
  • P013C O2 Sensor Slow Response – Rich to Lean (Bank 2 Sensor 2)
  • P013D O2 Sensor Slow Response – Lean to Rich (Bank 2 Sensor 2)
  • P013E O2 Sensor Delayed Response – Rich to Lean (Bank 1 Sensor 2)
  • P013F O2 Sensor Delayed Response – Lean to Rich (Bank 1 Sensor 2)
  • P0140 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
  • P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
  • P0142 02 Sensor Circuit Malfunction (Bank 1 Sensor 3)
  • P0143 02 Sensor Circuit Low Voltage (Bank 1 Sensor 3)
  • P0144 02 Sensor Circuit High Voltage (Bank 1 Sensor 3)
  • P0145 02 Sensor Circuit Slow Response (Bank 1 Sensor 3)
  • P0146 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)
  • P0147 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
  • P0148 Fuel Delivery Error
  • P0149 Fuel Timing Error
  • P014A O2 Sensor Delayed Response – Rich to Lean (Bank 2 Sensor 2)
  • P014B O2 Sensor Delayed Response – Lean to Rich (Bank 2 Sensor 2)
  • P014C O2 Sensor Slow Response – Rich to Lean (Bank 1 Sensor 1)
  • P014D O2 Sensor Slow Response – Lean to Rich (Bank 1 Sensor 1)
  • P014E O2 Sensor Slow Response – Rich to Lean (Bank 2 Sensor 1)
  • P014F O2 Sensor Slow Response – Lean to Rich (Bank 2 Sensor 1)
  • P0150 02 Sensor Circuit Malfunction (Bank 2 Sensor 1)
  • P0151 02 Sensor Circuit Low Voltage (Bank 2 Sensor 1)
  • P0152 02 Sensor Circuit High Voltage (Bank 2 Sensor 1)
  • P0153 02 Sensor Circuit Slow Response (Bank 2 Sensor 1)
  • P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
  • P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
  • P0156 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)
  • P0157 02 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
  • P0158 02 Sensor Circuit High Voltage (Bank 2 Sensor 2)
  • P0159 02 Sensor Circuit Slow Response (Bank 2 Sensor 2)
  • P015A O2 Sensor Delayed Response – Rich to Lean (Bank 1 Sensor 1)
  • P015B O2 Sensor Delayed Response – Lean to Rich (Bank 1 Sensor 1)
  • P015C O2 Sensor Delayed Response – Rich to Lean (Bank 2 Sensor 1)
  • P015D O2 Sensor Delayed Response – Lean to Rich (Bank 2 Sensor 1)
  • P0160 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
  • P0161 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
  • P0162 02 Sensor Circuit Malfunction (Bank 2 Sensor 3)
  • P0163 02 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
  • P0164 02 Sensor Circuit High Voltage (Bank 2 Sensor 3)
  • P0165 02 Sensor Circuit Slow Response (Bank 2 Sensor 3)
  • P0166 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)
  • P0167 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)
  • P0168 Fuel Temperature Too High P0169 Incorrect Fuel Composition
  • P0170 Fuel Trim Malfunction (Bank 1) P0171 System too Lean (Bank 1)

The most common issues for lean codes are:

1. Vacuum leaks – check for failed or loose vacuum lines, leaking intake gaskets, intake air tubes loose or any other source of un-metered air leaks (leaks after the Mass Air Flow Sensor)
2. Restricted fuel filter or bent/pinched fuel system lines
3. Incorrect input from other sensors, such as the Mass Air Flow Sensor, which may not always drop a separate code
4. Engine misfire – Yes I know this one may seem weird. You might think that if there is a misfire then you will have all that unburned fuel and it should read rich; right? Well the O2 sensors read only oxygen content in the exhaust, so if you have all that unburned fuel from incomplete combustion then, you guessed it, you also have all that unburned oxygen. High O2 content in exhaust equals a lean reading!

There are also some other possibilities such as an internally leaking EGR system, (but this will typically set a separate code). A leak in the exhaust system before the O2 sensor will also cause incorrect readings. And always check for after- market modifications. These can throw a wrench into the works! The only other possibilities (however unlikely), are wiring issues, computer concerns or a bad O2 sensor! There now that I’ve said it, on to rich codes.

The possible causes of rich codes are:

  1. A leaking or faulty fuel injector.
  2. Fuel injector driver in computer shorted, or wiring short for injectors (likely a ground short).
  3. Leaking or faulty fuel pressure regulator or restricted return line.
  4. Faulty evaporative emissions system – bleeding fuel vapors into engine (not commanded by computer).
  5. On newer models a faulty fuel pump or fuel pump driver module.
  6. Faulty readings from other sensors such as a Mass Air Flow Sensor. You may actually be getting more air than the MAF tells the computer.
  7. Exhaust leaks before the sensor will cause erratic readings.
  8. After market components or performance chips.
  9. And yes, if I dare say it, possibly a computer, wiring issue or even a faulty O2 sensor!.

The other codes we should address are those related to the sensors located after the catalytic converter. Though these may appear identical to the oxygen sensors pre-converter, they perform an entirely different task and are known as Monitors. The only job of these sensors is to “monitor” the efficiency of the catalytic converters. The readings from these sensors should be much more stable and not fluctuating like the front O2 sensors.

The computer compares the readings from the oxygen sensors (pre cats) and the monitors (post cat) to determine if the catalytic converters are doing their job and “cleaning” the exhaust. You never want to replace a monitor for a rich/lean concern as they have no bearing on these codes. As the converters begin to fail, you will see the monitors voltage readings follow the oxygen sensor readings. Technically these are all “oxygen sensors” but it is important to distinguish the difference between pre-converter & post converter sensors, so I find it easiest to stick to calling the back ones monitors.


  • 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 Range/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 B Circuit Low Input
  • P0188 Fuel Temperature Sensor B Circuit High Input
  • P0189 Fuel Temperature Sensor B Circuit Intermittent
  • P018A Fuel Pressure Sensor “B” Circuit
  • P018B Fuel Pressure Sensor “B” Circuit Range/Performance
  • P018C Fuel Pressure Sensor “B” Circuit Low
  • P018D Fuel Pressure Sensor “B” Circuit High
  • P018E Fuel Pressure Sensor “B” Circuit Intermittent/Erratic
  • P018F Fuel System Over Pressure Relief Valve Frequent Activation
  • P0190 Fuel Rail Pressure Sensor A Circuit
  • P0191 Fuel Rail Pressure Sensor A Circuit Range/Performance
  • P0192 Fuel Rail Pressure Sensor A Circuit Low Input
  • P0193 Fuel Rail Pressure Sensor A Circuit High Input
  • P0194 Fuel Rail Pressure Sensor A 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