U0140 Diagnostic Trouble Code

U0140 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a U0140 diagnostic trouble code may include:

Cherry red hot catalytic converter
Poor acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Hesitation upon acceleration

Possible Causes :

Some aftermarket accessories and performance modifications
A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed. 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. You might continue by connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and freeze frame data.

Process Tips

Diagnostic trouble code U0140 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 U0140.

Fortunately, U0140 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U0140 Trouble Code For Specific Cars

U0140 Aymesa Gala Aux Heater Start Counter Overrun/System Locked (same as below ?)
U0140 Mercedes Slk 230 Air Bag Diagnostic Monitor Ground Circuit Open
U0140 Mercedes E 320 ABS Valve Power Relay Circuit Failure
U0140 Mercedes-benz 15 Air Bag Driver Inflator Circuit Resistance Low on Squib - Loop #2
U0140 Paterson Model 33 Driver Side Satellite Communication Circuit Short to Ground
U0140 Packard 400 DPFE Sensor Hoses Reversed
U0140 Rolls-royce Phantom Hydraulic Pump Relay Circuit Low