U3878 Toyota Avensis Diagnostic Trouble Code

U3878 Toyota Avensis code definition:
U3878 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Toyota Avensis.

U3878 Toyota Avensis is defined as Ignition Coil B Primary/Secondary Circuit Malfunction.This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II tool, or vehicles made since 1996 up to present. 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 U3878 Toyota Avensis diagnostic trouble code may include:

Corroded or damaged connector
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Lack of power
Diminished fuel efficiency

Possible Causes :

Faulty IMRC actuator/sensor
A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.

Common Misdiagnoses

Vehicle Speed Output Circuit Problem
Cruise Control Servo Indicates Low Problem
A/C System High Pressure High Temperature Problem
PCM Stack Overrun Problem
Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors. Pull the connectors apart and carefully look at the terminals (the metal parts) inside the connectors. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.

Process Tips

Diagnostic trouble code U3878 Toyota Avensis 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 U3878 Toyota Avensis.

Fortunately, U3878 Toyota Avensis is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.