C0021 Mercedes-benz S Class Diagnostic Trouble Code

C0021 Mercedes-benz S Class code definition:
C0021 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code for Mercedes-benz S Class.

C0021 Mercedes-benz S Class is defined as Knock Sensor Circuit Range Performance (Bank 1 or Single Sensor). This refers to camshaft timing, which in this case is over-retarded. Other symptoms that may indicate this problem are when the Check Engine Light illuminates and when there is a visible lack of engine power.

Symptoms

Symptoms of a C0021 Mercedes-benz S Class diagnostic trouble code may include:

Reduction in engine performance, especially at low RPM levels
Vacuum leak on the engine
Diminished fuel efficiency
Engine surge

Possible Causes :

Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
An air leak forward of the DPF will change the sensor readings resulting in the code
Dirty air cleaner element Damaged DPF

Common Misdiagnoses

TP Sensor Learn Not Complete Problem
Low Coolant Circuit Problem
Cruise Control System - Vehicle Accel Too High Problem
TFP Valve Position Switch-Drive Without Drive Ratio Problem
Problem

Repair Processes :

Oxygen sensors signal the engine management computer the amount of oxygen present in the exhaust, which is used in determining and controlling the fuel ratio. It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.

Process Tips

Diagnostic trouble code C0021 Mercedes-benz S 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 C0021 Mercedes-benz S Class.

Fortunately, C0021 Mercedes-benz S Class is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.