Independent Auto Diagnostics, Tech Analysis and Smart Insights
OBD2 Error Codes
Modern vehicles use the OBD2 diagnostic system to monitor engine performance, emissions and electronic systems. When a fault is detected, the car stores a Diagnostic Trouble Code (DTC) such as P0420, P0171 or P0300.
On this page you will find the complete index of OBD2 error codes, along with explanations of how the diagnostic system works and links to detailed troubleshooting guides.
DiagnozaBAM provides technical resources for drivers, mechanics and automotive enthusiasts who want to understand vehicle diagnostics and fix problems faster.
What is an OBD2 Error Code
An OBD2 error code is a standardized diagnostic code generated by the vehicle’s Electronic Control Unit (ECU).
When the onboard system detects a malfunction, it stores a code and activates the Check Engine Light on the dashboard.
The P0217 code is a diagnostic trouble code that indicates the engine has exceeded its safe operating temperature. This condition is critical, as overheating can cause severe engine damage if not addressed immediately. When the engine control unit (ECU) detects excessively high coolant or engine temperatures, it triggers the P0217 code. Understanding the P0217 code […]
The P0215 code is a diagnostic trouble code that indicates a malfunction in the engine shutdown solenoid system. This component is responsible for controlling fuel flow to the engine, particularly in diesel engines, where it plays a critical role in stopping the engine safely. When the engine control unit (ECU) detects a fault in this […]
The P0214 code is a diagnostic trouble code that indicates a malfunction in the cold start injector 2 system. This component plays an important role during engine startup, especially in low-temperature conditions, by delivering additional fuel to ensure proper combustion. When the engine control unit (ECU) detects abnormal behavior in this system, it triggers the […]
The P0216 code is a diagnostic trouble code that indicates a malfunction in the injection timing control circuit. This issue is most commonly found in diesel engines, where precise fuel injection timing is critical for proper combustion, performance, and emissions control. When the engine control unit (ECU) detects irregularities in this system, it triggers the […]
The P0213 code is a diagnostic trouble code that indicates a malfunction in the cold start injector 1 circuit. This component plays a crucial role during engine startup, especially in cold conditions, by providing additional fuel to ensure proper combustion. When the engine control unit (ECU) detects an issue with this injector or its circuit, […]
The P0212 code is a diagnostic trouble code that indicates a malfunction in the fuel injector circuit for cylinder 12. This issue affects the precise delivery of fuel into the combustion chamber, which can lead to engine misfires, reduced power, and increased fuel consumption. When the engine control unit (ECU) detects abnormal electrical activity in […]
The P0211 code is a diagnostic trouble code that indicates a malfunction in the fuel injector circuit for cylinder 11. This issue affects how fuel is delivered into the engine, leading to misfires, rough performance, and reduced efficiency. When the engine control unit (ECU) detects abnormal electrical behavior in the injector circuit, it stores the […]
The P0210 code is a diagnostic trouble code that indicates a malfunction in the fuel injector circuit for cylinder 10. This problem affects how fuel is delivered into the combustion chamber, leading to poor engine performance, misfires, and increased fuel consumption. When the engine control unit (ECU) detects irregularities in the electrical signal controlling the […]
The P0209 code is a diagnostic trouble code that signals a malfunction in the fuel injector circuit for cylinder 9. This issue directly affects fuel delivery and combustion, leading to noticeable engine performance problems. When the engine control unit (ECU) detects abnormal electrical behavior in the injector circuit, it triggers the P0209 code and stores […]
The P0208 code is a diagnostic trouble code that signals a problem with the fuel injector circuit on cylinder 8. This issue can lead to engine misfires, reduced performance, and increased fuel consumption if not addressed promptly. In modern vehicles, precise fuel delivery is essential, and when the injector circuit fails, the engine control unit […]
The P0207 code indicates a malfunction in the fuel injector circuit for cylinder 7. The Engine Control Unit (ECU) monitors each injector individually, and when it detects abnormal voltage, resistance, or signal behavior, it triggers this fault. Fuel injectors are electronically controlled valves that deliver precise amounts of fuel into each cylinder. If the circuit […]
The P0206 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected a fault in the electrical circuit controlling the fuel injector for cylinder 6. Each fuel injector is controlled individually by the ECU using a pulse signal that regulates: injection timing fuel delivery quantity combustion efficiency emissions output When the ECU […]
The P0205 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected a fault in the electrical control circuit of the fuel injector for cylinder 5. In modern engines, each injector is individually controlled by the ECU through a pulse-width modulated signal. This signal determines: precise injection timing fuel delivery volume combustion […]
The P0204 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected a fault in the electrical circuit controlling the fuel injector for cylinder 4. Fuel injectors are electronically controlled valves that deliver fuel into the combustion chamber. The ECU sends precise electrical pulses to each injector to regulate: injection timing fuel […]
The P0202 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected a fault in the electrical circuit controlling the fuel injector for cylinder 2. Fuel injectors are electronically controlled components that deliver fuel into the combustion chamber. The ECU controls each injector individually by sending precise electrical pulses that regulate: injection […]
The P0203 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected a fault in the electrical circuit controlling the fuel injector for cylinder 3. Fuel injectors are electronically controlled components that deliver fuel into each cylinder. The ECU sends precise electrical pulses to control injector operation, including: injection timing fuel quantity […]
The P0200 diagnostic trouble code (DTC) means the engine control unit (ECU) has detected a fault in the fuel injector circuit. Fuel injectors are electronically controlled components that spray fuel into the engine. The ECU sends electrical signals to each injector to control: fuel delivery injection timing engine performance emissions When the ECU sees an […]
The P0183 trouble code indicates that the fuel temperature sensor “A” circuit is sending a voltage signal that is higher than expected to the ECU. A “high input” condition usually means the signal is close to maximum voltage (typically near 5V), which suggests: Open circuit Broken wiring Faulty sensor The ECU interprets this as extremely […]
The P0184 trouble code indicates an intermittent signal problem in the fuel temperature sensor “A” circuit. This means the ECU is receiving a signal that is: Unstable Fluctuating unexpectedly Temporarily lost or inconsistent Unlike P0182 (low input) or P0183 (high input), this code points to a signal that comes and goes, not a constant fault. […]
The P0182 trouble code indicates that the fuel temperature sensor “A” circuit is reporting a low voltage signal to the ECU. A “low input” condition usually means the ECU is receiving a voltage that is below the expected range, often close to 0V, which suggests: Short to ground Faulty sensor Wiring issue The ECU interprets […]
The P0181 trouble code indicates that the signal from the fuel temperature sensor “A” is outside the expected operating range or behaving inconsistently relative to engine conditions. Unlike P0180 (circuit fault), P0181 is a performance issue, meaning the sensor is working but sending implausible or unstable data to the ECU. How the Fuel Temperature Sensor […]
The P0180 trouble code indicates a malfunction in the fuel temperature sensor “A” circuit. The Engine Control Unit (ECU) relies on this sensor to monitor the temperature of the fuel and adjust injection timing, fuel quantity, and combustion parameters accordingly. When the ECU detects an abnormal voltage or signal from the fuel temperature sensor circuit, […]
The P0175 trouble code indicates that the engine is running too rich on Bank 2, meaning there is too much fuel and not enough air in the air-fuel mixture. Bank 2 = the side of the engine that does NOT contain cylinder 1 The ECU detects this condition using oxygen (O2) sensors A rich mixture […]
The P0154 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 2 Sensor 1 is showing no activity. This is the upstream sensor, located before the catalytic converter, responsible for real-time air-fuel mixture monitoring. Normally, the sensor should: rapidly switch voltage between lean and rich respond instantly to throttle changes provide continuous feedback […]
The P0153 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 2 Sensor 1 is responding too slowly to changes in exhaust gas composition. This is the upstream sensor, located before the catalytic converter, and it plays a critical role in real-time fuel control. Normally, the sensor should: switch rapidly between lean and […]
The P0152 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 2 Sensor 1 is sending a high voltage signal to the Engine Control Unit (ECU). This is the upstream sensor, located before the catalytic converter on Bank 2, responsible for monitoring the air-fuel mixture. Normal voltage range: 0.1V → lean 0.9V → […]
The P0151 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 2 Sensor 1 is sending a low voltage signal to the Engine Control Unit (ECU). This is the upstream sensor, positioned before the catalytic converter on Bank 2. It plays a key role in regulating the air-fuel mixture. Normal O2 sensor voltage: […]
The P0150 OBD2 code indicates a malfunction in the oxygen sensor circuit for Bank 2 Sensor 1. This sensor is the upstream O2 sensor, located before the catalytic converter on Bank 2 (the side of the engine that does NOT contain cylinder 1). Its role is critical: monitors air-fuel mixture sends real-time data to ECU […]
The P0146 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 1 Sensor 3 is showing no activity. This sensor is located downstream of the catalytic converter and is used to monitor emissions and confirm catalytic converter performance. Normally, an O2 sensor should: generate a voltage signal react (even slowly) to exhaust gas […]
The P0145 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 1 Sensor 3 is responding too slowly to changes in exhaust gas composition. This sensor is located downstream of the catalytic converter and is responsible for monitoring emissions stability and catalytic converter efficiency. Normally, an O2 sensor should: react to changes in […]
The P0144 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 1 Sensor 3 is sending a high voltage signal to the Engine Control Unit (ECU). This sensor is located downstream of the catalytic converter and is responsible for monitoring emissions performance. Normal O2 sensor voltage range: 0.1V → lean 0.9V → rich […]
The P0143 OBD2 code indicates that the oxygen sensor (O2 sensor) on Bank 1 Sensor 3 is reporting a low voltage signal to the Engine Control Unit (ECU). This sensor is positioned downstream in the exhaust system, typically after the catalytic converter. Its role is to monitor exhaust gases and confirm emission system performance. Normal […]
The P0142 OBD2 code indicates a malfunction in the oxygen sensor circuit for Bank 1 Sensor 3. This sensor is typically located further downstream in the exhaust system, after the catalytic converter. Not all vehicles are equipped with a third oxygen sensor, but on those that are, it plays a role in: monitoring extended emissions […]
The P0141 OBD2 code indicates a malfunction in the heater circuit of the oxygen sensor (O2 sensor) located on Bank 1 Sensor 2. This is the downstream oxygen sensor, positioned after the catalytic converter. Its role is to monitor exhaust gases and verify catalytic converter efficiency. Modern oxygen sensors are equipped with an internal heating […]
The P0140 code indicates that the oxygen sensor (O2 sensor) located on Bank 1 Sensor 2 is showing no activity. This sensor is positioned after the catalytic converter (downstream sensor) and its main role is to monitor catalytic converter efficiency, not to control fuel mixture like the upstream sensor. When the Engine Control Unit (ECU) […]
The P0124 code indicates that the Engine Control Unit (ECU) has detected an intermittent or unstable signal from the Throttle Position Sensor (TPS) circuit. Unlike P0122 (low input) or P0123 (high input), this code appears when the TPS signal is inconsistent, fluctuating, or temporarily lost. The TPS is critical for: throttle response fuel delivery engine […]
The P0123 code indicates that the Engine Control Unit (ECU) has detected a high voltage signal from the Throttle Position Sensor (TPS). A high input signal means the ECU interprets the throttle as wide open, even when the accelerator is not pressed. TPS operation: low throttle → low voltage high throttle → higher voltage In […]
The P0122 code indicates that the Engine Control Unit (ECU) has detected a low voltage signal from the Throttle Position Sensor (TPS). A low input signal means the ECU interprets the throttle as closed or near closed, even when the accelerator is pressed. TPS operation: low throttle → low voltage high throttle → higher voltage […]
The P0121 code indicates that the Engine Control Unit (ECU) has detected that the Throttle Position Sensor (TPS) signal is outside the expected range or not consistent with other sensor data. The ECU continuously compares TPS data with inputs from sensors such as: Mass Air Flow (MAF) Manifold Absolute Pressure (MAP) Engine RPM If the […]
The P0120 code indicates that the Engine Control Unit (ECU) has detected a malfunction in the Throttle Position Sensor (TPS) circuit. The TPS monitors the position of the throttle valve and sends this information to the ECU to control: fuel injection ignition timing throttle response transmission shifting (in some vehicles) When the signal is missing, […]
The P0119 code indicates that the Engine Control Unit (ECU) has detected an intermittent or unstable signal from the Engine Coolant Temperature (ECT) sensor circuit. Unlike P0117 (low input) or P0118 (high input), this code appears when the signal is inconsistent or fluctuates unexpectedly. The ECT sensor is essential for: fuel injection control ignition timing […]
The P0117 code indicates that the Engine Control Unit (ECU) has detected a low voltage signal from the Engine Coolant Temperature (ECT) sensor. A low input signal usually means the ECU interprets the engine as extremely hot, even when it may not be. The ECT sensor works based on resistance: high temperature → low resistance […]
The P0116 code indicates that the Engine Control Unit (ECU) has detected that the Engine Coolant Temperature (ECT) sensor signal is outside the expected range or not changing as it should. Unlike circuit faults (P0115), this code appears when the signal is illogical compared to engine behavior, for example: engine warms up too slowly temperature […]
The P0115 code indicates that the Engine Control Unit (ECU) has detected a malfunction in the Engine Coolant Temperature (ECT) sensor circuit. The ECT sensor measures the temperature of the engine coolant and sends data to the ECU to control: fuel injection ignition timing cooling fan operation cold start enrichment When the ECU detects a […]
The P0114 code indicates that the Engine Control Unit (ECU) has detected an intermittent signal from the Intake Air Temperature (IAT) sensor circuit. Unlike P0112 (low input) or P0113 (high input), this code appears when the signal is unstable or fluctuates unexpectedly. The IAT sensor plays a key role in: air-fuel mixture calculation ignition timing […]
The P0113 OBD2 code indicates that the Engine Control Unit (ECU) has detected a high voltage signal from the Intake Air Temperature (IAT) sensor. The IAT sensor measures the temperature of the air entering the engine. This information is critical for calculating: air density fuel injection timing ignition timing A high input signal usually means […]
The P0111 diagnostic trouble code (DTC) indicates that the Engine Control Unit (ECU) has detected that the Intake Air Temperature (IAT) sensor signal is outside the expected operating range or does not correlate with other engine parameters. Unlike a circuit fault, this code appears when the sensor is working but the readings are implausible or […]
The P0109 diagnostic trouble code (DTC) indicates that the engine control unit (ECU) has detected an intermittent or unstable signal from the Manifold Absolute Pressure (MAP) sensor circuit. This means the signal from the MAP sensor is not constant, fluctuating unexpectedly due to electrical or mechanical issues. The ECU relies on stable MAP data to […]
