The Biosensor Scope is a special weapon sight in the Resident Evil 4 remake that works like a thermal camera, spotting heat-emitting creatures, including Ganados, Novistadors, as well as animals and fish. It is a reimagined version of the Infrared Scope from the original 2005 game, featuring slight design changes while retaining the same core function.
What makes the Biosensor Scope a critical weapon attachment in the Resident Evil 4 remake is its ability to reveal the parasite inside enemies. For instance, the Plaga inside a Regenerador can be spotted and destroyed using this item. If that sounds intriguing, the following guide is for you; it explains how to get the Biosensor Scope in both the main campaign of the Resident Evil 4 remake and the Separate Ways DLC.
Resident Evil 4 Remake: Weapon Tier List
Need some help figuring out which are the best weapons in the Resident Evil 4 remake? This Weapon Tier guide is exactly what's needed.
Updated on June 7, 2026, by Mohsen Baqery: After reviewing this post, I noticed some missing instructions, especially for obtaining the Biosensor Scope in the Resident Evil 4 remake DLC. As such, I rewrote most parts, added an overview table, and reworked the step-by-step instructions so players can obtain this valuable weapon attachment with little to no hassle.
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Biosensor Scope Specs (Resident Evil 4 Remake) |
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Also Known as |
Thermal Scope, Infrared Scope (OG title) |
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Description |
A special scope that highlights biological entities. Can be mounted onto rifles and some automatic weapons. |
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Biosensor-Compatible Weapons |
SR M1903, Stingray, CQBR, LE 5 |
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Availability |
Chapter 13 (Main Campaign), Chapter 5 (Separate Ways DLC) |
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Location |
Incubation Lab (Main Campaign), Castle Gregorio's Waterway (Separate Ways DLC) |
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Size |
2×2 |
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Sale Price |
3,000 Pesetas |
How to Get the Biosensor Scope with Leon
- Start by interacting with the power station in the Labs
- Switch the Dissection Room's power on
- Head to the Dissection Room and solve its power puzzle
- Grab the level 1 key card in the Dissection Room
- Go back to the power station, and, this time, switch the Freezer's power on
- After solving the Freezer's electronic terminal puzzle, head inside and put the level 1 key card inside the overwrite machine
- Take the level 2 key card from the machine and head to the Incubation Lab
- The Biosensor Scope can be found sitting on a desk inside the Incubation Lab's control room. This is where Leon is asked to restore Resident Evil 4's missing wrench.
If you have purchased the treasure map for Resident Evil 4's Chapter 13 locations, a gem icon will appear in the Incubation Lab. This icon marks the location of the Biosensor Scope.
Try to avoid the frozen Regeneradors in the test tubs. If you shoot one, the others will also become hostile. Given how difficult Regeneradors are to kill in the Resident Evil 4 remake without the Biosensor Scope, it is better to engage them only after you have unlocked the attachment.
What's That Weapon?
Identify the silhouettes before time runs out.
Identify the silhouettes before time runs out.
How to Get the Biosensor Scope in the Separate Ways DLC
- Chapter: Five
- Location: Drainage Control Room (Castle Gregorio's Waterway)
In Chapter 5 of Resident Evil 4 Remake's Separate Ways DLC, Ada must go through Castle Gregorio's Waterway, which is an underground section in the Castle area. She eventually comes across a pathway leading to a Merchant site, though it is blocked by water. To unblock the path, she must go to the Drainage Control Room, and that's where she can find the Biosensor Scope sitting next to the gate valve handwheel.
How to Equip the Biosensor Scope
Here's a quick, step-by-step guide:
- Press the [Y] button to open the inventory.
- Hover over the Thermal Scope and press the [A] button to access its options.
- Select "Parts."
- If you have compatible weapons in your inventory, they will appear in the list. These include the SR M1903, Stingray, CQBR, and LE 5.
The only way to switch the Biosensor off is by detaching it. There is no quick on/off toggle.
Best Weapons for the Biosensor Scope
An ideal weapon for the Biosensor Scope is the Stingray, one of the best rifles in the Resident Evil 4 remake. With this attachment, the Stingray becomes one of the most effective weapons for taking down Regeneradors because it reveals the Plagas inside their bodies, and shooting these hidden parasites instantly kills them.
Another solid option is the LE 5 submachine gun in Resident Evil 4 remake. Its fast fire rate helps compensate for the movement of tough enemies like Regeneradors, allowing you to keep pressure on them before they close the distance. It also gives you more room for error since you can land multiple shots quickly before needing to reload.
Things Resident Evil 4 Remake Doesn't Tell You About the Biosensor Scope
- Use the Biosensor Scope to spot nearby Novistadors. These insect-like creatures can hide in plain sight, but scanning areas with the Biosensor Scope reveals their location, letting you take them out before they attack.
- Hunt fish and snakes. The Biosensor detects any living creature that emits heat, making it useful for finding fish and snakes and collecting extra Resident Evil 4 currency.
- Shoot the weak point of Araña-type Plagas. When these parasites emerge from an enemy's head, you can one-shot them by targeting their weak point, which the Biosensor reveals.
Resident Evil 4
OpenCritic Reviews
- Genre(s)
- Survival Horror
