Looked up in the shop manual:
P1640- Roll Over detection disabled due to Inertial Measurement Unit (IMU) malfunction
P1695 - CAN fault - lost communication with instrument panel
P16A2 - Engine ECM detects IMU present but with signal error
It points to the IMU having a problem. If the fault is cleared after 40 start cycles the MIL light will clear or just use TuneECU and clear them and see if they come back.
Shop Manual Instructions:
Make sure ABS modulator connector is secure. Check for associated DTC C1713, perform tests for this DTC. Reset DTCs, if problem persists contact Triumph service.
Description of system:
IMU (if fitted) The Inertial Measurement Unit measures the following:
• Longitudinal acceleration
• Vertical acceleration
• Lateral acceleration
• Pitch rate
• Yaw rate
• Roll rate
From these measurements the IMU calculates the motorcycle's lean angle. The IMU outputs are used for multiple systems, for example, optimised cornering ABS (OCABS) and fall detection. If the IMU is fitted, the fall detection switch will not be fitted.
Here Comes the Bad News:
On the Rocket 3, the IMU is mounted on the frame (typically under the tank or near the ABS modulator). Replacement involves:
1. Remove bodywork to access the IMU
Usually:
- Seat off
- Tank lifted or removed
- Side panels off
The IMU is a small rectangular sensor with a single multi‑pin connector.
2. Disconnect the IMU harness
Triumph uses locking connectors — depress the tab and slide the connector out.The manual specifically tells you to verify the
ABS modulator connector is secure when diagnosing IMU faults , because the IMU shares CAN communication paths.
3. Unbolt the IMU
It’s mounted with 2–3 small bolts.Important: The IMU must be mounted
perfectly level. Triumph uses fixed mounting points so alignment is automatic.
4. Install the new IMU
Bolt it in, reconnect the harness.
5. Clear DTCs and verify communication
The manual says:
- Clear DTCs
- If the problem persists, contact Triumph service
This is because the IMU is part of the CAN network, and the ECM must detect it and validate its signals.
6. Perform IMU calibration (dealer tool only)
Triumph’s diagnostic system (Triumph OBD/DealerTool) performs:
- IMU initialization
- Zero‑angle calibration
- CAN handshake
TuneECU
cannot perform IMU calibration — it can only clear codes.
Your current tab shows the IMU‑related fault codes:
- P1640 – Roll‑over detection disabled due to IMU malfunction
- P1695 – CAN fault, lost communication with instrument panel
- P16A2 – ECM detects IMU present but with signal error
These codes strongly suggest:
- Either the IMU is unplugged, water‑damaged, or internally failed
- Or the CAN line between IMU → ABS modulator → ECM is compromised
Because the IMU is part of the safety system (cornering ABS), Triumph requires calibration after replacement.
Here's The Good News:
Before replacing the IMU, check these first
These are directly from the manual:
- Check ABS modulator connector (IMU shares CAN path)
- Check for DTC C1713 (ABS/IMU communication fault)
- Clear DTCs and see if they return
A loose ABS connector is
far more common than a failed IMU.