B1540 Diagnostic Trouble Code

B1540 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 B1540 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
Rich or lean exhaust

Possible Causes :

Faulty IMRC actuator relay (if equipped)
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
Defective ECU strategies or components will prevent proper regeneration

Repair Processes :

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. 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 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.

Process Tips

Diagnostic trouble code B1540 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 B1540.

Fortunately, B1540 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

B1540 Trouble Code For Specific Cars

B1540 Nissan Xterra Cylinder #7 High To Low Side Open
B1540 Mercer 35 Air Suspension LF Height Sensor Circuit Failure
B1540 Toyota Picnic PAD Warning Lamp Circuit Short to Battery
B1540 Suzuki Esteem
B1540 Triumph 2000 Passengers Seat Belt Buckle Switch Circuit Short to Battery
B1540 Isdera 033 SCP (J1850) Invalid or Missing Data for Odometer
B1540 Tvr 7 Power Door Memory Lock Relay Circuit Failure