Guide to Side Quests
Since I have encountered numerous questions about side quests on the forums, I decided to write this guide. Spoilers are kept to a minimum to help solve quest-related issues without revealing the plot. I will not describe obvious quests; I will only detail those that may cause difficulties. For convenience, they are divided by time periods.
Note: N7 missions are given by Samantha Traynor and take place on the same maps that are present in multiplayer. It’s best to collect the other side quests first before heading on the N7 mission.
List of N7 missions:
N7: "Cerberus" Base
N7: "Cerberus" Lab
N7: "Cerberus" Assault
N7: "Cerberus" Abductions
N7: Fuel Reactors
N7: Communications Hub
Time Period Before Palaven:
Shrike Abyss: Prothean Obelisk
Where to get it: Diplomat Volus at the Embassies
Where to find it: planet Taliss Fia, Urla Rast system, Shrike Abyss
Citadel: Panacillin for Aliens
Where to get it: Dr. Raveen, Huerta Hospital
Where to find it: Located during the first N7 mission. To the right of the landing point, up the stairs, and then right again.
Citadel: Pillars of Strength
Where to get it: Batarians' Preacher at the Docks
Where to find it: planet Har'Shan, Harsa system, Hawk's Nest
Citadel: First Regiment Flag
Where to give it to: Turian in the "Purgatory" bar
Where to find it: planet Diseris, Castel system, Apian Cross
Time Period Before Sur'Kesh:
Benning: Evidence
Where to get it: Ambassador Dominic Osoba, Embassies
Where to find it: found in the N7 mission on Benning.
Citadel: Enhanced Power Grid
Where to get it: Alison, "Purgatory" bar
Where to find it: Can be purchased at "Spectre Requests" after the N7 mission on Tuchanka, or found on that mission. They are located at the terminal next to the weapon control terminal.
Citadel: Barla Von
Where to get it: Appears after talking to Liara at the café, then obtained from the Volus Barla Von. He is standing in the bank in the Presidium Commons.
Where to find it: planet Rotla, Dranek system, Krogan DMZ
Citadel: Biotic Interfaces
Where to get it: Asari Scientist, Huerta Hospital
Where to find it: Found in Grissom Academy, terminal after meeting Octavia.
Citadel: Prototype Components
Where to get it: Lead Scientist, Huerta Hospital
Where to find it: planet Metalonto, Aquila system, Ismar's Edge
Citadel: Book of Plenik
Where to get it: Evil Accountant Volus, Presidium Commons
Where to find it: planet Iruna, Aru system, Eton Cluster
Citadel: Heat Stabilizers
Where to get it: Salarian Sally, Presidium Commons
Where to find it: Can be purchased at "Spectre Requests" after the attack on the Citadel.
Time Period Before and During Tuchanka:
Citadel: Krogan's Last Message (for some reason it does not show up in quests)
Where to give it to: Asari Ereb, Presidium Commons, located behind the counter at the "Meridian" market
Where to find it: Found during the "Attic Traversal: Rachni" mission on the corpse of the Krogan behind one of the webs.
Citadel: Cerberus Weapon Schematics
Where to give it to: SBC Officer, Presidium Commons
Where to find it: Found during the "Tuchanka: Bomb" mission
Time Period After the Citadel Attack:
Citadel: Cerberus Codes
Where to get it: Turian Officer Dellk, Embassies
Where to find it: Can be purchased at "Spectre Requests" after the mission "N7: Communications Hub"
Citadel: Reaper Code Fragments
Where to get it: Asari Strategist, Embassies
Where to find it: Found during the mission "Renoch: Geth Destroyers"
Celean Nebula: Alune Rings
Where to get it: Asari Consultant, Huerta Hospital
Where to find it: planet Nevos, Theolia system, Celean Nebula
Citadel: Chemical Burn Treatments
Where to get it: Salarian Dr. Cylon, Huerta Hospital
Where to find it: Found during the "N7: Fuel Reactors" mission, or can be purchased at "Spectre Requests" after it.
Citadel: Military Medications
Where to get it: Dr. Chakwas/Chloe Michelle on the "Normandy"
What to do: Go to the docks on the Citadel and meet with the Turian Taktus to negotiate an exchange.
Citadel: Cerberus Poison for Turians
Where to get it: Salarian Doctor, Huerta Hospital
Where to find it: Found during the "Arrae: Former Cerberus Scientists" mission
Valhalla Threshold: Prothean Data
Where to get it: Alliance Soldier
Where to find it: planet Gorvug, Paz system, Valhalla Threshold
Aida Center: Prothean Sphere
Where to get it: Refugee, Docks
Where to find it: planet Gei-Hinnom, Sheol system, Aida Center
Citadel: Broken Dispensers
Where to get it: Doctor from the refugee camp, Docks
Where to find it: Upon exiting the nook with the doctor - turn left. On the way, you will encounter only three dispensers. They look like this:
Dekuuna: Codex of the Ancients
Where to get it: Evil Elcor, at the entrance to "Purgatory"
Where to find it: planet Dekuuna, Fontes system, Celian Nebula
Nimbus: Library in Ashe
Where to get it: Asari Military Instructor, "Purgatory" bar
Where to find it: planet Karkosa, Aganu system, Nimbus
Athena Nebula: Hesperian Statue
Where to get it: Asari Scientist, Presidium Commons
Where to find it: planet Polissa, Vernio system, Athena Nebula
Citadel: Injured Batarian
Where to get it: Overhear a conversation in the Presidium Commons
What to do: Go to the docks and talk to the NPC medical staff.
Citadel: Remains of a Calypsosaurus
Where to get it: Military Strategist, Presidium Commons
Where to find it: planet Intai'Sey, Phoenix system, Ro Argos
Citadel: Jamming Technology
Where to get it: SBC Officer, Presidium Commons
Where to find it: Can be purchased at "Spectre Requests" after the mission "Renoch: Admiral Koris"
Aida Center: Karza Obelisk
Where to get it: Researcher, Presidium Commons
Where to find it: planet Kopis, Oplos system, Aida Center
Citadel: Asari Widow
Where to give it to: Vesra, Presidium Commons
Where to find it: Found during the mission "Mesana: Distress Signal"
Dekuuna: Evacuation of Elcors
Where to get it: Elcor, Embassies, near the elevator, to the right of it
What to do: I had already been on Dekuuna when this quest appeared. It could be completed immediately, without additional flights anywhere.
I would like to describe a few quests (which will give you a bit more trouble) separately:
Quest of Aria T'Loak (divided into three sub-quests):
Note: Aria is located in the "Purgatory" bar, on the lower levels, to the right of the entrance. She gives all three tasks at once.
1. Aria: "Blue Beacons"
Let’s talk to Darner Vosque in the docks. He will send us to Turian General Orak. The situation can be resolved in two ways: kill the general (short way), or deal with the weapon suppliers for him (which requires some effort). If you choose the second path, go to the Salarian merchant named Kanik. He is stationed at the market "Meridian" in the Presidium Commons. The Salarian can acquire weapons for the general, but doesn’t want money for it. He wants rare artifacts in exchange. They can be found here: planet Vana, Vular system, Hawk's Nest.
2. Aria: "Blood Pack"
We meet with Narl in the Presidium Commons, in the only open room where Housing is. We watch a cutscene.
3. Aria: "Eclipse"
We go to Bailey at the Embassies. You can convince him to release the insane Asari (short way), or appoint her second-in-command - Salarian Sain - as head of "Eclipse". If you chose the second way, head to the Presidium Commons at the SBC post and speak with the Turian. We watch a cutscene. We go to the docks, and speak with Sain.
Citadel: Hanar Diplomat:
Starts with a letter. Spectre Yodnum Bau asks for help. We meet him on the Citadel in the Embassies. After talking to him, we go to the Spectre terminal and enable surveillance in the Hanar embassy. The first terminal is located in the Embassies:
The second one is similarly located in the docks. The third is also there, near dock E28. After finishing with the terminals, we head to the Embassies. We watch a cutscene.
Quest of Engineer Adams / Citadel: Thermal Pipe GX12:
Samantha Traynor will tell you that Adams would like to speak with us. We talk. The pipe can be purchased on the Citadel (Presidium Commons, Bank), or at the shuttle dock on the "Normandy" at the "Elkoss Combine Arsenal" store. This pipe is referred to as "Heat Dissipation Contour".
Citadel: Inspirational Stories:
A Salarian named Solik at the entrance to the docks will ask us to take photos of the tough lives of refugees for a documentary film. Photos can be taken in the following places:

Citadel: Batarian Codes:
The quest starts with a conversation with Officer Knowles near the SBC offices (Presidium Commons). We go to the Spectre terminal. We enable tracking. The first console is located in Huerta Hospital, the second in the "Normandy" dock, and the third in the docks. If we use the Hero/Outlaw dialogue option - we receive remains of the Batarian fleet.
Citadel: Volus Ambassador:
Starts after reading a letter from Primarch Victus. At the Spectre terminal, we establish the whereabouts of Din Corlak. We go to the Embassy guard. We listen to the recordings, find a bug under the table. We go to the apartments, try to open one door. It’s locked. We go to the opposite door. We meet an old acquaintance. We talk to him in the docks, and he joins our army.
Well, that's all the side quests that may cause difficulties. Finally, a bit of humor:
