U0308 Ford S-max Diagnostic Trouble Code

U0308 Ford S-max code definition:
U0308 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Ford S-max.

U0308 Ford S-max 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. The spark should have a light tan color. If the sensor probe comes with white and chalky parts, this means it has been lagging between switching phases, and should be replaced.

Symptoms

Symptoms of a U0308 Ford S-max 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
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.
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

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
Kick-Down Switch Failed Short Problem
Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit Problem

Repair Processes :

You might continue by connecting the scanner to the vehicle diagnostic connector and retrieving all stored codes and freeze frame data. 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 U0308 Ford S-max 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 U0308 Ford S-max.

Fortunately, U0308 Ford S-max is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.