B0742 Diagnostic Trouble Code

B0742 is a kind of OBD-II Diagnostic B-Body 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 B0742 diagnostic trouble code may include:

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
Faulty or damaged wiring
Hesitation upon acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

An air leak forward of the DPF will change the sensor readings resulting in the code
Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
Defective ECU strategies or components will prevent proper regeneration

Repair Processes :

Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble. 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. 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.

Process Tips

Diagnostic trouble code B0742 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 B0742.

Fortunately, B0742 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

B0742 Trouble Code For Specific Cars

B0742 Suzuki Sea Forenza Mirror Driver Left Circuit Short To Battery
B0742 Subaru B9 Left Front Center Sensor Circuit Failure
B0742 Suzuki Sidekick Mirror Driver Left Circuit Short To Ground
B0742 Bmw 2500 Camshaft Position Sensor Circuit Range/Performance
B0742 Bmw 640 Climate Control A/C Lock Sensor Failure
B0742 Steyr 500 Lamp Seat Belt Circuit Short To Ground
B0742 Alfa Romeo Rz Air Bag Crash Sensor #2 Feed/Return Circuit Failure