Bosch 13475 Oxygen Sensor - Downstream

Bosch Actual OE Oxygen Sensor for BMW Downstream Fitment

Bosch Part Number 13475 is a narrow-band heated oxygen sensor built for downstream applications on select BMW models. It provides precise air-fuel-ratio feedback to the ECU, helping maintain stable combustion control and lower emissions across changing operating conditions.

As part of Bosch’s Actual OE Oxygen Sensor line, this sensor reflects Bosch’s long OE development history in oxygen sensing technology. The design uses a ceramic sensing element, controlled heater operation, and high-temperature-resistant materials for consistent signal output in demanding exhaust environments.

Key Features

• Specific-fit Bosch oxygen sensor for downstream placement
• Narrow-band heated sensor type for closed-loop fuel control
• Round male connector with 4 terminals and 4-wire harness
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Wiring harness included; harness length measures 19.1 in
• Standard replacement grade for OE-style service work
• Metal housing with steel finish for exhaust-side durability

Detailed Description

Bosch 13475 is an Actual OE Oxygen Sensor engineered for BMW downstream locations where accurate exhaust-gas feedback is required after the catalytic converter. It is a narrow-band heated oxygen sensor with a threaded 18 mm mounting design, making it a direct service part for vehicles that use this configuration. This part number 13475 is listed for BMW 540i, M5, Z8, 740i, 740iL, 750iL, 840Ci, and 850Ci applications in the model years shown below.

Bosch’s switching-type oxygen sensor design measures the air-fuel ratio and sends that information to the ECU so the engine can maintain proper closed-loop operation. For BMW 540i and BMW 740i/740iL service, as well as BMW M5 and Z8 downstream replacement work, Bosch 13475 supports accurate sensor response under heat and vibration. This part cross-references Bosch OE-style applications for the same fitment family.

What This Sensor Helps Address

• Check engine light caused by a failing downstream oxygen sensor
• Slow or inaccurate oxygen sensor signal response
• Emissions test failures related to exhaust monitoring
• Rough closed-loop fuel control from degraded sensor output
• Exhaust-side sensor wear from heat and vibration exposure

Installation Notes and Tips

Confirm downstream placement before ordering, since this sensor is specific fit and not universal. Verify the 18 mm thread size, 22 mm hex size, round connector shape, and 4-wire configuration against the original part. Use proper oxygen sensor service tools and inspect the exhaust bung threads before installation to ensure a secure seal.

• Fits 1997-2003 BMW 540i, Downstream
• Fits 2000-2003 BMW M5, Downstream
• Fits 2000-2003 BMW Z8, Downstream
• Fits 1997-2001 BMW 740i, Downstream
• Fits 1996-2001 BMW 740iL, Downstream
• Fits 1995-1998 BMW 750iL, Downstream
• Fits 1996-1997 BMW 840Ci, Downstream
• Fits 1995-1997 BMW 850Ci, Downstream

Quality Assurance

Bosch supplies this oxygen sensor as part of its Actual OE Oxygen Sensor line, drawing on more than five decades of OE development and aftermarket service experience. The sensor is built to Bosch’s OE-proven standards for signal accuracy, heater control, and durability in demanding exhaust conditions.