OE O2 Sensors replaced by VolksTech O2 with Production Video


First of all,

The video is showing that VolksTech manufacturing process of 1 set of Oxygen Sensors for factory-owned car.

Fully Detailed 2mins Production line Video is at the bottom of this blog, so make sure you don’t miss it ๐Ÿ™‚ Big thanks in advance to all future billionaires who watch our blogs.


There are more than 50 cars in total owned by VolksTech factory colleagues, However, it is very metaphysical that, those cars never have oxygen sensor failures. Therefore, the failure of this factory-owned car oxygen sensor is a very special case to verify our products in daily road-test, rather than on cars specially bought for testing.

Application Car Model:

Fourth Generation of Ford Mondeo, year 2008 2.3 iVCT Gasoline sports

Engine: Duratech-HE 2.3 iVCT  165hp/6500rpm   21.7kgm/4200rpm

Ford Car

OE Number of Oxygen Sensors

Upstream (Front) Oxygen Sensor:


0 258 006 927/928


Downstream (Back) Oxygen Sensor:


0 258 006 927/928

Cable Length: 660 mm


Terminals are shown as below pictures:

Front And Rear Sensor Terminals
Front Sensor Termial-Green & Rear Sensor Terminal-Blue

Failure Mode, Symptoms and Cause

a. Rough Engine Idle

When driving at low speed or idling, the car has obvious vibration. Acceleration is slow when step on the accelerator pedal.   

Cause:  A bad oxygen sensor will send incorrect information to the ECU. This may result in the injection of more fuel to the engine than required, causing the engine to stall. This, in turn, induces the engine to experience a rough idle.

b. Engine hesitation

When push the accelerating Pedal, car speeds up very slowly, feeling no power.

Cause: When the amount of air-fuel mixture sent to the engine is not optimal, the combustion in the engine cylinders get affected, which can cause the engine to misfire. This usually occurs either when the engine accelerates or idles.

c. The engine warning light is on.

Car diagnostic scanner shows that the failure is with oxygen sensor.


With Wrench, it is relatively easier to reach and unscrew the front sensor.

Take Of The Front Sensor

The rear sensor is after the Catalytic converter which is deep as shown in photo below, and the wrench is often blocked by the Catalytic converter.

Therefore, it took a big effort from colleagues to take off the rear sensor in a 37-degree environment, a big thanks to the team.

Downstream Sensor After The Catalytic Converter

ROOT Cause

We can observe that the Oxygen sensors turn white and it is due to silicone poisoning or antifreeze contamination.  This car was having the antifreeze leakage issue, so that is like to be the Root Cause.

Polluted To White

Last but not least, The Replacement parts manufacturing Process:

This is we are very willing to show you, so I directly attached another Production line video, Have Fun!

AFTER INSTALLATION , the car is running well with VolksTech Oxygen sensors now.

Engine has neither hesitation nor Idling, and we recorded the mileage for further tracking.

Last photo are the original sensors made in Germany, they made a good job during the years. 

The Failed Sensors Has White On The Top

Aftermarket and OE manufacture of Oxygen Sensor, Exhaust Gas Temperature Sensor and NOx Sensor

Over 3000 OE Numbers & Bosch/Delphi cross reference with Pics.

Get Catalogue of Oxygen Sensor / EGT Sensor / NOx Sensor and Top Sellers info NOW.

Over 3000 OE Numbers & Bosch/Delphi cross reference with Pics.

Get Catalogue of Oxygen Sensor / EGT Sensor / NOx Sensor and Top Sellers info NOW.

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We will contact you within 1 working day, please pay attention to the emailย โ€œsales01@volkst.comโ€.ย 

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