AFR Gauge and Wideband LSU Lambda Sensor Kit 4.9

Wideband AFR gauge kit — finally read your mixture in real time

This AFR gauge kit combines an air/fuel ratio display with a LSU 4.9 wideband lambda sensor, part number 0258017025. On a modified, turbocharged, or simply reprogrammed engine, it is the instrument that tells you whether the mixture is rich or lean the moment you are flat out, instead of finding out after a failure.

Why a wideband sensor instead of a stock sensor

• Reading range from 8 to 20 AFR: the stock sensor is only reliable around stoichiometry, the wideband reads the entire useful range.
• Red digital display: numbers readable in broad daylight, with a peripheral scale to track the trend at a glance.
• Bosch LSU 4.9 sensor: the market standard for wideband measurement, more stable over time than previous generations.
• Complete kit: gauge, sensor, two harnesses, welding ring and manual, nothing else to order.
• Two Mode and Sel buttons: display settings accessible without disassembly.

What is a wideband oxygen sensor used for

An oxygen sensor measures the amount of oxygen remaining in the exhaust gases and deduces the richness of the intake mixture. The stock sensor, known as a threshold sensor, is used by the ECU to maintain stoichiometry under partial load: it does not provide information on a clearly rich or lean mixture. A wideband lambda sensor, on the contrary, covers the entire range, making it the basic tool for engine mapping, carburetor tuning, or wide-open throttle monitoring. The displayed air/fuel ratio allows you to validate a reprogramming job or detect an intake leak before it costs you dearly.

Technical specifications

Type: wideband AFR gauge with sensor. Model: X series 30-0300. Sensor: LSU 4.9, part number 0258017025. Display: digital red with a scale from 8 to 20. Power supply: vehicle 12 V circuit. Contents: 1 gauge, 1 wideband sensor, 2 harnesses, 1 welding ring, hardware and manual. Compatibility: universal on gasoline engines, to be checked according to the vehicle before installation.

Installation: the three steps that matter

Allow 2 to 4 hours with the welding of the ring. First step, the sensor position: weld the ring on the exhaust line after the turbo or the manifold, orienting the sensor between 10 and 2 o'clock to prevent condensation from accumulating in it. Second step, the power supply: take a +12 V after ignition and a clean ground on the chassis, never on a painted point. Third step, the routing of the harnesses: keep them away from hot parts and ignition harnesses to avoid interference. Let the sensor heat up for about twenty seconds before considering the reading valid. This installation affects the exhaust line and the electrical circuit: entrust it to a professional if you are not equipped.

Frequently asked questions

What is the difference between a wideband sensor and a 4-wire sensor?
A wideband has an additional pumping cell that allows it to measure richness across the entire range, and not just around 14.7.

Does the sensor replace the stock one?
No. It is added on a dedicated tap and leaves the stock sensor in place for the ECU.

Where to weld the ring on the exhaust?
Downstream of the turbo or manifold, on a straight section, orienting the sensor upwards to protect it from condensates.

Does the gauge need to be calibrated?
Open-air calibration is recommended at the first power-up, sensor out of the exhaust, according to the provided manual.

Is it compatible with a diesel?
The AFR measurement is designed for gasoline engines. On diesel, the reading does not have the same tuning meaning.

Stop tuning your engine blindly: order your wideband AFR gauge kit.

Type: Wideband AFR gauge with lambda sensor
Model: X series 30-0300
Sensor: LSU 4.9, ref. 0258017025
Range: 8 to 20 AFR
Display: Red digital
Power supply: 12 V
Contents: Gauge, sensor, 2 harnesses, welding ring, manual
Compatibility: Universal gasoline, to be checked according to the vehicle
Condition: 100% New