P0171 GMC Fuel Trim System Lean Bank 1

Possible causes – Intake air leaks– Faulty front heated oxygen sensor– Ignition misfiring– Faulty fuel injectors– Exhaust gas leaks– Incorrect fuel pressure– Lack of fuel– Faulty Mass Air Flow (MAF) sensor– Incorrect Positive Crankcase Ventilation (PCV) hose connection Tech description If the P0171 is combined with the P0174 code, it’s very likely that the problem…

P2188 GMC Fuel Trim System Rich at Idle

Possible causes – Leaking fuel pressure regulator– Leaking fuel injector When is the obd code mean? The average long term fuel trim values at idle are less than -30 percent for 10 seconds Symptoms – Engine Light ON (or Service Engine Soon Warning Light) P2188 GMC OBD Code Description The engine control module (ECM) controls…

P0128 GMC Engine Coolant Temperature Below Thermostat Regulating Temperature

Possible causes – Leaking or stuck open thermostat– Low engine coolant level– Insufficient warm up time– Faulty engine coolant temperature sensor– Engine coolant temperature sensor harness is open or shorted– Engine coolant temperature sensor circuit poor electrical connection Tech description If cooling system is not leaking and the fluid level is OK, replacing the thermostat…

P0562 GMC System Voltage Low

Possible causes – Low battery cahrge– Battery defective– Loose or missing alternator drive belt– Faulty alternator– Open or short system voltage circuit Tech description Start by recharging or replacing the battery. When is the obd code mean? The Powertrain Control Module (PCM) has detected that the electrical system voltage level is too low. Symptoms –…

P0410 GMC Secondary Air Injection System Malfunction

Possible causes – Faulty Vacuum hoses damaged– Faulty Air Pump inoperative– Air bypass solenoid harness is open or shorted– Air bypass solenoid circuit poor electrical connection– Air bypass solenoid leaking/blocked or stuck open/closed– Air diverter valve leaking/blocked or stuck open/closed Tech description Visually inspect AIR pump and AIR bypass valve harness and connector, if connector…

P0608 GMC Vehicle Speed Output Circuit

Possible causes – Faulty Vehicle Speed Sensor– Vehicle Speed Sensor harness is open or shorted– Vehicle Speed Sensor circuit poor electrical connection When is the obd code mean? If the fault detection circuit senses a voltage other than what is expected, the fault line status changes causing the P0608 to set. Symptoms – Engine Light…

P0502 GMC Vehicle Speed Sensor Circuit Low Input

Possible causes – Faulty Vehicle Speed Sensor– Vehicle speed sensor harness or connectors is open or shorted– Vehicle speed sensor circuit poor electrical connection– Faulty Powertrain Control Module (PCM) When is the obd code mean? If the Powertrain Control Module (PCM) detects a low vehicle speed when there is a high engine speed in a…

P0500 GMC Vehicle Speed Sensor Circuit

Possible causes – Faulty Vehicle Speed Sensor– Vehicle speed sensor harness or connectors is open or shorted– Vehicle speed sensor circuit poor electrical connection– Faulty Powertrain Control Module (PCM) When is the obd code mean? The almost 0 km/h (0 MPH) signal from vehicle speed sensor is sent to Powertrain Control Module (PCM) even when…

P0503 GMC Vehicle Speed Sensor Circuit Intermittent

Possible causes – Faulty Vehicle Speed Sensor– Vehicle speed sensor harness or connectors is open or shorted– Vehicle speed sensor circuit poor electrical connection– Faulty Powertrain Control Module (PCM) When is the obd code mean? When the Powertrain Control Module (PCM) detects an unrealistically large drop in the vehicle speed, then DTC P0503 sets. Symptoms…

P1396 GMC Wheel Speed Sensor Circuit

Possible causes – Faulty Wheel Speed Sensor– Wheel Speed Sensor harness is open or shorted– Wheel Speed Sensor circuit poor electrical connection When is the obd code mean? The Engine Control Module (ECM) detects an invalid rough road signal from the wheel speed sensor. P1396 GMC OBD Code Description The road situation is estimated with…