B0518 Volvo S40 Diagnostic Trouble Code

B0518 Volvo S40 code definition:
B0518 is a kind of OBD-II Diagnostic B-Body Diagnostic Trouble Code for Volvo S40.

B0518 Volvo S40 is defined as Knock Sensor Circuit Range Performance (Bank 1 or Single Sensor). This refers to camshaft timing, which in this case is over-retarded. There are two wires dedicated for each coil; one is battery feed which usually comes from the distribution center, and the other one for the coil driver circuit from the PCM. The PCM grounds or ungrounds the circuit to activate or deactivate the coil.

Symptoms

Symptoms of a B0518 Volvo S40 diagnostic trouble code may include:

Misfire
Misfire
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

Fuel with a large percentage of sulfur will clog the DPF quickly
The Mass Airflow sensor will also cause this problem. Mass Airflow circuit malfunction.
An air leak forward of the DPF will change the sensor readings resulting in the code

Common Misdiagnoses

IC Circuit High Voltage Problem
Control Module Throttle Actuator Position Performance Problem
Air Conditioning (A/C) Clutch Feedback Circuit High Voltage Problem
Cruise Vehicle Speed/Set Speed Difference Too High Problem
PCM Stack Overrun Problem

Repair Processes :

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

Process Tips

Diagnostic trouble code B0518 Volvo S40 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 B0518 Volvo S40.

Fortunately, B0518 Volvo S40 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.