55236778 Car Oxygen Sensor For Alfa Romeo / Ferrari / Fiat / Fiat Powertrain

Technical Notes:

• This is a 4-wire heated oxygen sensor, designed as a "regulating probe" for precise air-fuel mixture control

• The heating element allows the sensor to reach operating temperature quickly, reducing cold-start emissions

• Compatible with both upstream (pre-catalyst) and downstream (post-catalyst) positions depending on vehicle application

This Lambda Sensor replaces the following Original Equipment Manufacturer (OEM) and interchange part numbers. Check your old sensor to confirm a match:

Aftermarket / Interchange Numbers:

Note: Always verify physical fitment before purchasing, as aftermarket interchange numbers may not be identical in all applications.

This Lambda Sensor is primarily used in vehicles from the Fiat Group, including Alfa Romeo, Fiat, Lancia, and Iveco. It is also compatible with certain Ferrari models.

Fitment Notes:

• This sensor is widely used across the Fiat-Chrysler (Stellantis) ecosystem

• Position (upstream/downstream) may vary by specific vehicle model and engine configuration

• Compatible with both petrol and natural power (CNG) engine variants

• Always verify with your vehicle's VIN and the position of your old sensor before ordering

Consider replacing your Lambda Sensor if you experience any of the following:

Check Engine Light (MIL) Illumination

• OBD-II fault codes related to oxygen sensor circuit:

  • P0130-P0167 series (O2 Sensor Circuit Malfunction)

  • P0420 / P0430 (Catalyst System Efficiency Below Threshold)

  • Manufacturer-specific codes for Fiat/Alfa Romeo/Lancia vehicles

Performance & Driveability Issues

• Incorrect mixture control – ECU receives inaccurate data, causing improper fuel trim adjustments

• Poor acceleration or hesitation – Engine struggles under load

• Rough idle or stalling – Unstable engine operation at low speeds

• Reduced engine power – Noticeable loss of performance, especially in turbocharged models (e.g., 1.4 T-Jet)

Fuel & Emissions Symptoms

• Increased fuel consumption – A faulty sensor can cause the engine to run rich, wasting fuel

• Failed emissions test – Incorrect air-fuel ratio leads to high pollutant output

• Black smoke from exhaust – Indicates excessively rich mixture

• Strong fuel odour – Unburned fuel in exhaust

Potential causes of sensor failure:

• Normal wear and tear – Replacement is typically recommended every 100,000 miles (160,000 km)

• Contamination – Oil, coolant, or silicone sealants can damage the sensing element

• Heater circuit electrical failure – Internal heating element stops functioning (common cause of P0030-P0037 codes)

• Physical damage – Impact from road debris or improper handling during installation

• Exhaust leaks – Upstream or downstream leaks can affect sensor readings

1. Confirm Fitment Before Purchasing

   • This is a direct-fit sensor for Fiat Group vehicles with a specific 4-pin connector

   • Always cross-reference your old sensor's part number, connector shape, and wire length before ordering

   • Compatible with OEM numbers: 55236778, 55218148, 46750245, 46751082, 46545432

   • Physical inspection of your original sensor is strongly recommended

2. Determine Position (Upstream vs. Downstream)

   • This part number (55236778) may function as either a regulating sensor (upstream/pre-cat) or diagnostic sensor (downstream/post-cat) depending on the specific vehicle application

   • Verify the location of your old sensor (Bank 1, Sensor 1 or 2) before ordering

   • Some applications may require two sensors (one for each bank or position)

3. Engine & Vehicle Variant Verification

   • Common compatible engines: 1.3, 1.4 T-Jet, 1.6 16V, 1.8 GT 16V, 2.4, 1100 cc

   • Also compatible with Natural Power (CNG) engine variants

   • Ensure your specific model year and engine code match the fitment guide

4. Aftermarket vs. OE Quality Note

   • This OE number (55236778) is used across Alfa Romeo, Ferrari, Fiat, Iveco, and Lancia vehicles

   • Aftermarket sensors using this cross-reference may vary in quality, wire length, and connector precision

   • For optimal performance, consider OE-spec components

5. Installation Tips

   • Allow the exhaust system to cool completely before removal to avoid burns and prevent thread damage

   • Use an O2 sensor socket (22mm or 7/8") to prevent stripping the sensor during removal/installation

   • Apply anti-seize compound to the threads of the new sensor (avoiding the sensor tip) to prevent seizing in the exhaust bung

   • Do not use silicone sealants near the exhaust system – contamination will destroy the sensor

   • Avoid touching the sensor tip – oils from your skin can contaminate the sensing element

   • Do not drop the sensor – the ceramic element can crack upon impact

   • Tighten to the correct torque – Typically 40-50 Nm (30-37 ft-lb)

   • Secure wiring harness with proper clips to prevent contact with hot exhaust components or moving parts

6. Replacement Interval

   • Lambda sensors degrade over time, often without triggering immediate fault codes

   • Replacement every 100,000 miles (160,000 km) is recommended to maintain:

     • Optimal fuel efficiency

     • Catalytic converter health and longevity

     • Proper emissions output

     • Smooth engine operation

7. Required Tools

   • O2 sensor socket (22mm / 7/8") or deep offset wrench

   • Ratchet and extension bar (for access)

   • Anti-seize compound (sensor-safe, if not pre-applied)

   • Jack and jack stands (if under-vehicle access requires lifting)

   • OBD-II scanner (to clear fault codes and verify operation after replacement)

8. Quantity Needed

   • 4-cylinder engines typically have 1-2 oxygen sensors

   • V6/V8 engines (including Ferrari applications) may have 2-4 sensors depending on configuration

   • Check your vehicle's exhaust configuration to determine how many sensors you need

9. Warranty

   • Quality Lambda Sensors typically come with a warranty period (commonly 1 year / 12 months)

   • Aftermarket sensors from manufacturers may offer varying warranty terms

   • Check with your specific retailer for their warranty terms and return policy

   • Important: Warranties may be voided if the sensor tip shows contamination from improper handling