P278B Nissan 200 Diagnostic Trouble Code

P278B Nissan 200 code definition:
P278B is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Nissan 200.

P278B Nissan 200 is described as Fuel System Too Rich, which basically means bank 1's oxygen sensor has detected a rich condition of fuel. This means there's not enough oxygen in the exhaust from too much fuel being delivered into the air and gas mixture for combusion. So if the problem persists despite of your diagnosis, then you should never hesitate to take your vehicle to your dealer or to a qualified mechanic.

Symptoms

Symptoms of a P278B Nissan 200 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

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 :

Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. 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.

Process Tips

Diagnostic trouble code P278B Nissan 200 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 P278B Nissan 200.

Fortunately, P278B Nissan 200 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.