Mercedes Sprinter Upstream Oxygen Sensor – Bosch | T1N / NCV3 OM647 & OM642 | #0035427118 (2003–2012)

A failed upstream oxygen sensor on a Mercedes Sprinter removes the primary exhaust gas feedback the ECU depends on to maintain correct air-to-fuel ratio — causing rough running, increased fuel consumption, reduced power, and fault codes that won't clear until the sensor is replaced. This is the Bosch upstream oxygen sensor for T1N Sprinters equipped with the OM647 diesel and early NCV3 Sprinters equipped with the OM642 V6 diesel, a direct replacement that restores accurate exhaust gas monitoring and proper engine management.

What This Part Does

The upstream oxygen sensor — also called a pre-cat or lambda sensor — is positioned in the exhaust stream before the catalytic converter and measures the oxygen content of the exhaust gases exiting the engine. The ECU uses this signal to evaluate combustion efficiency and make continuous fuel delivery corrections to maintain the optimal air-to-fuel ratio. On the OM642 V6, the engine has two exhaust banks, each with its own upstream sensor — both sensors must function correctly for balanced fuel control across all six cylinders. When a sensor's element ages, becomes contaminated by oil or coolant, or fails electrically, the ECU loses its primary feedback loop and defaults to open-loop fueling — causing the rough running, black smoke, and fuel economy loss that accompany uncorrected combustion.

Common Symptoms of a Failing Upstream Oxygen Sensor

• Check engine light with O2 sensor circuit or performance fault codes
• Rough idle or uneven power delivery from uncorrected air-to-fuel ratio
• Increased fuel consumption with no other identified cause
• Black smoke under acceleration from a fuel-rich condition
• Catalytic converter fault codes from upstream sensor data causing inefficient converter operation

When to Replace

Replace when the sensor is confirmed faulty by scan tool with active upstream O2 sensor fault codes. Also inspect and replace both upstream sensors together on the OM642 V6 — sensors age simultaneously and replacing only one leaves the other bank uncorrected.

T1N / NCV3 OM647 & OM642 Specific — VIN Verification Required

This sensor is for T1N Sprinters with the OM647 5-cylinder diesel and early NCV3 Sprinters with the OM642 3.0L V6 diesel. It is not compatible with NCV3 Sprinters equipped with the 2.1L OM651 or VS30 Sprinters. Always verify your engine code and VIN before ordering. Contact us and we'll confirm fitment before you buy.

Fitment

• 2003–2006 Mercedes-Benz / Dodge Sprinter 2500 / 3500 – OM647 Diesel (T1N)
• 2007–2009 Dodge Sprinter 2500 / 3500 – OM642 Diesel (NCV3)
• 2007–2008 Freightliner Sprinter 2500 / 3500 – OM642 Diesel (NCV3)
• 2010–2012 Mercedes-Benz Sprinter 2500 / 3500 – OM642 Diesel (NCV3)

✔ Upstream (pre-catalyst) position — front left and right
✔ OM642 V6: two sensors required — one per exhaust bank
✔ Always verify by VIN before ordering

Part Numbers

• Mercedes OEM: 0035427118 / A0035427118 / 003-542-71-18
• Cross-reference: 0258017018 / 234-5091 / 5135667AA
• Manufacturer: Bosch
• SKU: 0035427118