How to read fault codes on an Aiways U5
Short answer: you can read and clear standard powertrain codes on a U5 yourself, because the car uses a standard 16-pin OBD-II socket wired to its CAN network. A generic reader connects with no special access. What a generic reader cannot do is reach the body, battery-management or driver-assistance systems, or run the defined-value tests the manufacturer documentation assumes — so an empty scan is not proof of a healthy car. This page sets out exactly where that boundary sits, what the manual documents about the socket, and what has to go to a workshop with manufacturer-level diagnostics.
1. The socket is standard OBD-II — that is the good news
The Aiways U5 is fitted with a standard 16-pin OBD-II diagnostic socket. In the wiring documentation it carries the internal identifier BD99 (vehicle diagnostic interface), but electrically it is a normal OBD-II port: the CAN pair, permanent battery positive and ground all sit on the pins you would expect. That is why a common CAN dongle or handheld scan tool plugs straight in and talks to the car without any manufacturer handshake for the standard systems.
| Pin | Function | Notes from the wiring documentation |
|---|---|---|
| 16 | Permanent battery positive (B+) | Fed through the instrument fuse box and a 10 A fuse (IF40) |
| 6 | CAN-High | Brown/red conductor, routed to the gateway |
| 14 | CAN-Low | Brown/yellow conductor, routed to the gateway |
| 4 | Ground | Common ground point G203 |
| 5 | Ground | Common ground point G203 |
A note on the U6. The U6 also uses the BD99 socket, but adds DoIP / Ethernet on top of standard CAN — pins 3 and 11 for the RX pair, pins 12 and 13 for the TX pair, and the activation line on the CAN pins. The U6 is therefore accessible to Ethernet-capable tooling that the U5 is not. The U5 itself has no DoIP wiring in the documents we hold, so plan around plain CAN for the U5.
2. One documentation gap, stated honestly
Here is something worth knowing before you go looking. In the 2021 U5 wiring set, the data-communication section runs only from sheet P1 to P9 — there is no standalone OBD socket page, and the socket detail has to be read across from the earlier 2019 set. Only the U6 has a dedicated page for its Ethernet / DoIP connector.
The practical effect: we can give you the socket electrically, pin by pin, from the documents, but the documentation does not state the socket's physical mounting position in words. We are not going to invent a location we cannot point to a source for. It is a standard OBD-II connector, so approach it the way you would any car and confirm on your own vehicle.
3. What a generic reader can and cannot reach
This is the part that matters most, and it is where a lot of people waste money. A generic tool is an engine-and-powertrain reader first and foremost. It is not a whole-car diagnostic.
| System | Generic OBD-II reader | Manufacturer-level diagnostics |
|---|---|---|
| Powertrain / standard P codes | Yes — read and clear | Yes, plus guided tests and measured values |
| Body / B codes | No | Yes — with the manufacturer protocol and tool access |
| Battery-management system (BMS) | No | Yes — live data and defined-value checks |
| Driver assistance (ADAS) | No | Yes — including calibration after work |
| High-voltage and safety systems | No | Yes — and this must be a qualified workshop regardless |
| Defined-value measurement tests | No | Yes — comparing measured values against documented limits |
The manufacturer documentation sets the boundary clearly enough: it tells the technician to connect a diagnostic tool and select the module — but it does not name a tool brand or model, does not cover software accounts or authorisation, and does not publish the protocol-level service details. There is no manufacturer compatibility list for us to reproduce, and we will not pretend there is.
What that means in practice: an owner can read and clear standard powertrain codes. The moment a fault sits in the body, BMS or ADAS systems, or needs a defined-value check such as an overspeed threshold or an insulation test, it has to go to a workshop with the matching manufacturer diagnostics. We do not supply, recommend or facilitate unlocking, flashing or bypassing that access.
4. What the codes on this site actually cover
We publish 116 fault-code records for the Aiways U5, drawn across eight control units. Knowing the shape of that list tells you immediately why a generic reader can come back empty on a car that is clearly unhappy: only 34 of the 116 begin with P.
| Module | Records |
|---|---|
| Body Control Module (BCM) | 42 |
| ESP | 20 |
| Battery Management System (BMS) | 16 |
| Vehicle Control Unit (VCU) | 15 |
| Gateway | 14 |
| Motor Control Unit (MCU) | 7 |
| Integrated Charging System (OBC) | 1 |
| Electronic gear shift | 1 |
By code family, that is 34 P (powertrain), 37 B (body), 25 U (network) and 20 C (chassis) — so more than two-thirds of the list lives outside what an ordinary reader addresses. The set also carries a risk grading (75 high, 41 standard) and a drive recommendation (41 usually drivable, 63 inspect first, 12 do not drive), which is the question owners actually ask.
See all 116 Aiways U5 fault codes, graded by risk and drive guidance →
One honest caveat on coverage: 116 records is a partial picture, not the full factory set. A code that is not on our list may still exist on your car. If a workshop reads something we do not cover, send us the code and the VIN and we will look at it.
5. What "connect the diagnostic tool" means in the manual
The VCU and BMS diagnosis documents follow the same template, and it is worth seeing, because it shows what the manufacturer expects a tool to do:
- Connect the diagnostic tool and switch vehicle power to ON.
- Enter the system diagnostic function.
- Select the module you want — for example VCU or BMS.
- Select measured values.
- Check whether the reported parameters sit inside their specified range.
Step 5 is the one a generic reader cannot do. Take a concrete example: the VCU code P101100 is a vehicle overspeed fault, set when vehicle speed exceeds 180 km/h and cleared once it drops below 155 km/h. Reading that code is one thing; interpreting it means comparing a measured value against a documented limit, which is manufacturer-tool work — not a code lookup.
6. Manual document numbers are not part numbers
People ask us for the part that fixes a code, and it is worth separating two things that look alike. The numbers below are internal identifiers for sections of the workshop documentation — how Aiways files its own diagrams and procedures. They are not orderable part numbers, and searching for them at a parts counter will get you nowhere.
| Document number | What it identifies |
|---|---|
| 04776 | Data communication / diagnostic socket diagram, U5 2019 |
| 08984 | Diagnostic socket, U6 2022 |
| 1845391 / 407341 | Component-connector end views, 2021 / 2019 |
| 1787061 | DTC P101100 (vehicle overspeed) |
| 1807891 / 1807861 | Diagnostic-tool information, VCU / BMS |
| 380641 / 360321 | Diagnostic-tool information, gateway / instrument cluster |
The workshop manual identifiethose internal document numbers are not orderable references — they are how the manual labels its own pages — and the orderable reference for your car is confirmed from the VIN. If you need a specific component, send us the VIN and we will confirm the real reference and the version for your car.
7. Short answers
- Do I need a special tool just to read codes?
- No — for standard powertrain codes a normal OBD-II / CAN reader is enough, because the U5 has a standard 16-pin socket. The special tooling starts where body, BMS and ADAS systems do.
- My reader says no codes. Am I fine?
- Not necessarily. Most of the U5 codes we publish are body, network and chassis codes a generic reader never sees. "No standard powertrain fault" is the most a generic scan can promise.
- Can I clear a warning light myself?
- Standard stored powertrain codes, yes. But clearing is not fixing — if the cause is still there the code and the light come back. Record the code first.
- When must it go to a workshop?
- Any body, battery-management or driver-assistance fault, anything needing a measured value against a documented limit, and anything high-voltage or safety-related. Those need manufacturer-level diagnostics and a qualified technician.
- Do you sell or recommend diagnostic software?
- No. We supply parts. We do not provide, recommend or facilitate unlocking, flashing or bypassing manufacturer diagnostic access, and we do not exaggerate what a cheap reader can do.
Where this comes from. The socket pins, the U5 / U6 wiring differences, the module workflow and the P101100 example are drawn from the Aiways U5 workshop and wiring documentation we hold — the data-communication and diagnostic-socket diagrams, the VCU and BMS diagnostic-tool sections and the DTC sheets. The fault-code counts, risk grading and drive recommendations come from our own published Aiways U5 code index. Anything not covered by those sources — a tool brand or model, software authorisation, the socket's physical location as a written instruction — is left out rather than guessed. Wording is our own; we do not reproduce manual pages.
8. Related
- Aiways U5 fault codes — every code, its risk and whether you can drive
- Aiways U5 12V battery drain — why every warning light comes on at once
- How Aiways part numbers are structured
- Why one Aiways part has several OE references
- All Aiways U5 / U6 parts we supply
Read a code and need the part that fixes it? Send the code and the VIN and we will confirm the version that fits your car — get in touch.