C1991 Trouble Code

View C1991 obd/2 error code description and symptoms. C1991 engine photo

HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw.
The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S. Water in harness connector. Open VPWR circuit. Open GND circuit. Low battery voltage. Corrosion or poor mating terminals and wiring Damaged HO2S heater. Damaged PCM.

One example of this would be when an automatic vehicle in placed in gear. To prevent the added drag from the torque converter and transmission from reducing the idling speed, the PCM will command the idle control valve to allow more air to enter the engine, while at the same time, adjusting the injector pulse width to inject more fuel to suit the increased amount of air. Note that the idle air control valve is closed by the PCM when the throttle plate is opened to prevent excess air from entering the engine.

C1991 Error Code Repair Process :

When you turn on the ignition, the Service Engine Soon or Check Engine C1991 light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. If engine oil pressure sensor/switch circuit high voltage so, you'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the engine oil pressure sensor/switch circuit high voltage.

C1991 is a kind of Chassis Trouble Code

Diagnosing chassis noises can be one of the most frustrating problems technicians face. Fortunately, manufacturers have engineered noise, vibration and harshness (NVH) diagnostic techniques and equipment to find the source of the noise.

Common Causes of C1991

A common cause of code C1991 is the failure of Engine Oil Pressure Sensor/Switch Circuit High Voltage, but there are several other possible causes as well, such as ;

Exhaust tube
Engine Control Module (ECM)
Fuel injector leaks
Faulty oil control valve (OCV)

C1991 code for all cars

You can view according C1991 DTC for your car model. We selected several models to see obd2 solutions click and view it.

+C1991 Seat Altea

+C1991 Land Rover Serie I

+C1991 Avanti Sport

+C1991 Citroen Spacetourer

+C1991 Nissan 240

Engine OBD 2 Codes website is a freeware resource center for engine trouble codes.

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