P0121 Mercedes-benz Ml Class Diagnostic Trouble Code
P0121 Mercedes-benz Ml Class code definition:
P0121 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Mercedes-benz Ml Class.
P0121 Mercedes-benz Ml Class is described as Oxygen Sensor Circuit No Activity Detected Bank 2 Sensor 1. This code appears when the PCM (powertrain control module, also known as ECM or engine control module in other brands) remains at or close the 0.450 set voltage point. So if the problem persists despite of your diagnosis, then you should never hesitate to take your vehicle to your dealer or to a qualified mechanic.
Symptoms
Symptoms of a P0121 Mercedes-benz Ml Class diagnostic trouble code may include:
- Engine surge
- Blown fuse (if applicable)
- Lack of power
- The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
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Possible Causes :
- Defective ECU strategies or components will prevent proper regeneration
- The Mass Airflow sensor is a hot wire that senses the volume of air entering the intake manifold. The computer uses this information to control fuel mixture.
- Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
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Common Misdiagnoses
- Crankshaft Position Sensor Circuit Performance Problem
- TP Sensor Learn Not Complete Problem
- Low Coolant Circuit Problem
- Cruise Control System - Vehicle Accel Too High Problem
- Kick-Down Switch Failed Short Problem
Repair Processes :
Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector.
If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs.
Process Tips
Diagnostic trouble code P0121 Mercedes-benz Ml Class is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.
Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before P0121 Mercedes-benz Ml Class.
Fortunately, P0121 Mercedes-benz Ml Class is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.
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