Also replaces Bosch part numbers:
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17025
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0 258 017 025
Fitments:
Most 4.9 LSU Wideband Controller Gauge
AEM 30-4110 Digital Wideband UEGO Gauge
AEM 30-0300 Wideband UEGO AFR Gauge
AEM 30-0310 Wideband UEGO AFR Controller
Why You Need an LSU 4.9 Replacement
Wideband sensors live a tough life near hot exhaust gases, fuel vapor, condensation, and vibration. Symptoms of a worn sensor include:
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Slow AFR response
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Sudden lean/rich spikes
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Inaccurate AFR numbers
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UEGO controller error codes
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AFR drift after warm-up
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Unstable readings during boost
Replaces OE#:
17025, 0258017025, 304110, 300300, 300310
A fresh LSU 4.9 restores:
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Fast response time
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Accurate lambda/AFR readings
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Reliable data for tuning and safety
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Stable readings across temperature changes
This is essential for turbo, supercharged, or high-compression builds where fueling mistakes get expensive.
O2 Sensor Installation Steps
①Disconnect the battery
Prevent accidental short circuits.
②Locate the old sensor
Usually found on the exhaust manifold or pipe.
③Unplug the sensor connector
Carefully disconnect the wiring harness.
④Remove the old sensor
Use an O2 sensor socket or wrench to unscrew.
⑤Clean the sensor port
Remove any rust or debris from the threaded hole.
⑥Apply anti-seize compound (if not pre-applied)
On the threads only, avoid the sensor tip.
⑦Install the new sensor
Thread it in by hand, then tighten with a wrench (do not overtighten).
⑧Reconnect the sensor wiring
Plug the harness back in securely.
⑨Reconnect the battery
Restore power to the system.
⑩Start the engine and check for codes
Quality Guarantee:
12-Month Warranty
Key Features
Bosch LSU 4.9 Accuracy
The industry standard for modern wideband systems, delivering:
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Faster heater warm-up
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Stable AFR readings under boost
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Long sensor lifespan
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Consistent output for ECU+datalogging
Direct Plug-and-Play Connector
No cutting, splicing, or guessing.
Matches the original AEM harness style.
Wide Fuel Compatibility
Reads AFR and lambda on:
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Pump gas
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E85
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Methanol
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Race fuels
High-Temperature Durability
Built to survive extreme exhaust temps and vibration found in performance vehicles.
At Gledewen, we take pride in the quality of our products and in your satisfaction. If you have any problems, do not hesitate to contact us.
Installation Notes
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Install in a properly placed wideband O2 bung (at least 18” downstream from turbo).
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Do not mount at the bottom of the pipe—condensation will kill the sensor.
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Avoid running leaded race fuel often (it shortens sensor life).
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Ensure the sensor heater cycles properly before engine load.
Typical install time: 5–10 minutes.
Final Verdict
The LSU 4.9 Lambda WideBand O2 Sensor is the correct, high-accuracy replacement for AEM’s modern UEGO and X-Series wideband systems.
If your AFR readings are slow, erratic, or inconsistent, replacing the sensor is the fastest and most reliable fix.
For tuning, logging, boost safety, or daily performance monitoring—this is the sensor you trust.
freddy –
Worked perfectly with the aem afr gauge had to calibrate but after that worked perfectly
D –
Worked on 2013 Kia Soul. Had tried another brand that made car run worse so I’m happy this one fixed problem. I was concerned when I received the part because it didn’t have any markings on it at all but it worked well. Now just have to hope it keeps working 😉
Mr. Mohr –
Does not work properly.I installed it, and it gave no error.The heater came on and shows 22.4 AFR.When I drive, it never went away from 22.4.So I remembered that I had to calibrate it in “free air”.So, I took it back out and let it hang in free air, and recalibrated it.Now it will show 22.4 99% of the time. Only under full boost will it register anything lower than that, and then only for a second. Then, while under full boost (the lowest AFR levels), it jumps back up to 22.4.This one just doesn’t work, even after calibration.
Ivan –
👍
Andrew Horan –
It’s A wide band sensor. It fits how it should, it seems to be quite accurate as it is hooked up to an AEM gauge and my AFR readings are what I would expect them to be. The overall quality of the sensor is very high, the connector fit perfectly into my AEM wideband connector and it’s been on there for some time now and is still doing its job. Phenomenally. As far as installation of a wideband sensor, if you need to retain your second O2 sensor, you will need to buy an additional bung drill the whole weld the bung, and then install the O2 sensor like you would any other sensor. And as long as it’s not too far behind your second O2 sensor, your readings should be pretty good. Ideally you’d want The sensor to be plumbed in near your upstream O2 sensor but I have tti long tubes and my upstream sensor is not in my merge collector which seems kind of like a mishap on their end, but I digress. It’s a great sensor. It does its job. It seems to be very accurate and it’s a very good price. 10 out of 10 would recommend
amanda peryeà –
Seems pretty accurate and quality is decent. Has been installed ifor use with my aem x series. No codes and sensor reads as it should. Installation is straight forwards. Great value and price.
Tom G –
Why did you pick this product vs others?:LSU 4.9 is e85 compatible a upgrade from the LSU4.2
Mike –
Great sensor. Had an issue after quite some time and they were quick to respond and fixed things very fast. I will buy from these guys from now on. Plenty of wire length and thr fitment was excellent. Amazing customer service 👏
Marcos arturo –
producto de buena calidad
excelente producto
Amazon Customer –
Good
Good