If the engine temperature is unusually high or low, fault code P2181 will be recorded. The Engine Coolant Temperature sensor (ECT) is responsible for sending the engine temperature information to the Powertrain Control Module. The PCM uses this information to ...
Category: Diagnostic Trouble Codes
Welcome to our Diagnostic Trouble Codes Blog — your reference point for understanding what your car’s fault codes really mean.
Discover clear, easy-to-follow articles explaining OBD-II codes, common causes, symptoms, and recommended fixes across all major vehicle systems.
From check-engine lights and sensor faults to emissions and drivability issues, our content helps you move from code to cause with confidence.
Learn how to interpret fault codes correctly, avoid unnecessary repairs, and diagnose problems the smart way.
Ask4Auto Latest Articles
P0406 Exhaust Gas Recirculation (EGR) Sensor A Circuit High Fault: What is it?
The fault code P0406 is ‘Exhaust Gas recirculation (EGR), Sensor A Circuit High.’ When the powertrain control module detects high voltage from the exhaust-gas-recirculation position sensor (EGR), it triggers the fault code P0406. The EGR position sensors detect the position ...
P0405 Exhaust Gas Recirculation Sensor ‘A’ Circuit Low Fault: What is it?
EGR systems are used to control the emission of nitrogen oxides (NOx). The Engine Control Module (ECM), when the sensor that monitors the position of EGR valves sends lower voltage signals than normal, stores the P0405 error code in its ...
P0521 Engine Oil Pressure Sensor/Switch Range/Performance Fault: What is it?
The engine oil pressure should be in the correct range to keep it running smoothly. It is important to maintain the correct oil pressure to avoid wear and tear on moving parts in your engine. A problem is indicated by ...
P0400 Exhaust Gas Recirculation (EGR) Flow Malfunction Fault: What is it?
The P0400 code is displayed by your OBD-II scan tool if you detect a problem with the Exhaust Gas Recirculation system (EGR). If it detects a lower EGR flow than expected, the Powertrain Control Module stores the P0400 error code ...
P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage Fault: What is it?
Engine performance is dependent on ignition timing and the air-fuel ratio. The Engine Control Module (ECM/PSM) calculates both using information transmitted by various sensors, such as air intake, fuel injection, engine, and exhaust systems.The MAP or BARO sensor measures the ...
P0161 Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 2) Fault: What is it?
The fault code P0161 is a “Malfunction of the Oxygen sensor Heater Circuit” (Bank 2, Sensor 2). Bank 2, Sensor 2 will alert you to an issue with the heater circuit for the oxygen (O2) sensors. Modern oxygen sensors are ...
P0068 MAP/MAF – Throttle Position Correlation Fault: What is it?
Different sensors monitor the air intake of an engine. The MAP sensor measures air pressure inside the intake manifold. The MAF sensor calculates engine air flow volume, and the TPS sensor shows the position of throttle plate within the throttle ...
P0720 Output Shaft Speed (OSS) Sensor Circuit Malfunction Fault: What is it?
The on-board diagnostics system (OBD), which is installed in your vehicle, detects and saves 5-character fault codes to its memory. This allows you to identify possible faults in the vehicle and their causes. When the powertrain control or transmission control ...
P0087 Fuel Rail System Pressure Too Low Fault: What is it?
Fuel pressure is transferred from the fuel tank to the engine through the fuel line. Engine Control Modules (ECM/PCMs) regulate pressure levels by adjusting fuel pumps or fuel volume regulators, depending on how the fuel system is designed. The ECM ...