U140A Mercedes C 63 Diagnostic Trouble Code

U140A Mercedes C 63 code definition:
U140A is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Mercedes C 63.

U140A Mercedes C 63 is described as Oxygen Sensor Circuit No Activity Detected (Bank 1, Sensor 1). This means there's a problem in the front oxygen sensor on Bank 1, as the O2 sensor is inactive. If the car doesn't start, they will proceed by testing the voltage at the fuel pump connector and see if the fuel pump relay, fuse, and PCM circuitry should be inspected.

Symptoms

Symptoms of a U140A Mercedes C 63 diagnostic trouble code may include:

Diminished fuel efficiency
Fuel pressure too high
Malfunction Indicator Lamp (MIL) illuminated
Hesitation upon acceleration

Possible Causes :

A plugged converter will cause of host of driveability problems as well as set this code. A severely plugged converter will result in the inability to increase rpm when under load. Look for a code such as P0421 -- catalytic converter efficiency below threshold if the converter indicating a faulty converter.
Dirty air cleaner element Damaged DPF
Faulty IMRC actuator/sensor

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 :

If all testing has passed so far yet you still have the same code, check your scan tool and see if it can open and close the IMRC valve. 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. Look for damage to the tank indicating impact that may have damaged the fuel pump or sender.

Process Tips

Diagnostic trouble code U140A Mercedes C 63 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 U140A Mercedes C 63.

Fortunately, U140A Mercedes C 63 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.