C121F BMW Fault Code
Check C121F OBD Fault Code ReasonBMW HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw.
The BMW 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.
C121F Code Symptoms :
When you turn on the ignition, the Service Engine Soon or Check Engine C121F 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 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 C121F!
Diagnosis And Repairing C121F
C121F OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.
How to fix C121F code ?
- Damaged camshaft position (CMP) sensor
- Faulty Camshaft Position Sensor
- Damaged VCT phaser
- Incorrect fuel filler cap used
Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code C121F, so consult the manual to locate the brake fluid reservoir.
Bear in mind that a low fluid level can set code C121F on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.
