The Bosch LSU 4.9 is the wideband lambda sensor used across the Bosch Motorsport ECU range — the MS 6 EVO and MS 7 ECUs include two direct LSU 4.9 interfaces as standard, allowing closed-loop wideband lambda control without an external controller. It is also the sensor specified by virtually every major standalone wideband lambda controller (AEM, Innovate, Link, PLX Devices) and is the reference standard for motorsport AFR measurement.
The LSU 4.9 measures oxygen concentration from λ 0.65 (rich, approximately 9.3:1 AFR for gasoline) to effectively open lean air — covering the full stoichiometric, rich mixture, and lean mixture operating ranges needed for calibration and race tuning. The sensor element is a planar dual-cell design: a pump cell and a Nernst cell work together to maintain a controlled electrochemical state at the measurement gap, from which lambda is calculated continuously.
At 930 °C continuous exhaust gas temperature rating (1,030 °C short-term), the LSU 4.9 survives at manifold-proximity mounting points — critical for fast sensor response during transient conditions. Backpressure above 2.5 bar begins to affect accuracy, so turbocharged installations should position the sensor downstream of the turbine rather than in the high-pressure pre-turbine section.
The 95 cm wire length reaches the ECU or lambda controller from a standard exhaust manifold or downpipe mounting point without extension leads.
Technical Specifications
| Property | Value |
|---|---|
| SKU / Part number | 0258017025 (0 258 017 025) |
| Sensor type | Wideband planar dual-cell (LSU = Lambda Sensor Universal) |
| Lambda range | 0.65 to open lean (infinite) |
| Exhaust gas temperature (continuous) | 930 °C |
| Exhaust gas temperature (short-term) | 1,030 °C |
| Exhaust gas backpressure | < 2.5 bar (accuracy reduces above this) |
| Hexagon/body max temperature | 600 °C |
| Thread | M18×1.5 |
| Wire length | 95 cm (~100 cm) |
| Weight | 120 g |
| Connector | 6-pin Bosch LSU (Jetronic family) |
Applications
| Application | Notes |
|---|---|
| ECU wideband lambda input | Direct input to Bosch MS 6 EVO, MS 7 ECUs (2 per ECU) |
| Closed-loop lambda control | Main lambda feedback for fuelling corrections |
| Wideband controller input | Compatible with all major standalone lambda controllers |
| Dyno tuning | Industry standard for AFR measurement during mapping |
| Per-cylinder or per-bank | One sensor per bank for independent lambda balance |
Related Products
- LSU 4.9 Lambda Sensor Connector Kit — mating 6-pin connector with pins and seals
- MS 6.4 EVO ECU — 2 × direct LSU 4.9 inputs built in
- MS 7.4 ECU — 2 × direct LSU 4.9 inputs built in
- Bosch Motorsport C70 Data Logger — can log lambda via CAN from lambda controller
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