U0156 Diagnostic Trouble Code

U0156 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 U0156 diagnostic trouble code may include:

Poor acceleration
Cherry red hot catalytic converter
Possible spark knock (detonation / pre-ignition)
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.

Repair Processes :

If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. 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 U0156 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 U0156.

Fortunately, U0156 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U0156 Trouble Code For Specific Cars

U0156 Twombly Cyclecar Power Supply #2 Circuit Short to Ground
U0156 Koenigsegg Cc Servo Motor Potentiometer Coolair Circuit Failure
U0156 Porsche 993 Fuel Level Sensor Circuit Malfunction
U0156 Fiat Fiorino Lamp Seat Belt Circuit Short To Ground
U0156 Triumph 2.5-litre Passengers Seat Belt Buckle Switch Circuit Open
U0156 Kia Kee Seat Track Position Switch Circuit Resistance Out of Range
U0156 Mazda 3 Transmission Transfer Case Contact Plate 'B' Short Circuit To Ground