# Throttle & Controls Diagnosing throttle response faults, headlight faults, horn faults and control-related error codes. --- ## Related error codes | Code | Meaning | | --- | --- | | **E08** | Throttle Error | | **E13** | Front Light Error | | **E02** | Brake Error | Full definitions: [Display & Error Codes](https://wiki.cemotoride.com/link/332). --- ## Symptom: throttle not responding ### 1. Confirm the bike is not in 0 gear This is the most common cause. On the D-series, the display lights up showing **0 gear** when the power is switched on, and in 0 gear the vehicle does not work. Press the **"+" key** to select a gear above 1. ### 2. Confirm drive mode Parameter **P10** controls how the throttle behaves: - `0` — Power drive: output is determined by the power gear, and **the handlebar is invalid**. - `1` — Electric drive: driven by the handlebar; the power gear is invalid. - `2` — Both coexist (electric drive is invalid in zero-start state). If the throttle appears dead but the bike otherwise works, check that **P10 is not set to 0**. See [Display & Settings](https://wiki.cemotoride.com/link/330). ### 3. Throttle body and housing - **Free return:** release the throttle and confirm it snaps back to zero immediately. A throttle that sticks is a safety hazard — stop riding and replace it. - **Cable:** check for a kinked, frayed or overtightened cable. - **Housing:** check for cracks from impact. - **Grip alignment:** the throttle grip plane should align with the installation stop line — the **zero line** — on the grip. Misalignment can preload the throttle. ### 4. Connector and signal - Reseat the throttle connector at both ends. - Check for corrosion or water ingress in the connector. - A throttle that reads a valid but incorrect signal at rest will trigger **E08 Throttle Error**. **Video:** *E08 Error — Check the Throttle Before Replacing Parts* — see [Technical Guides](https://wiki.cemotoride.com/link/336). ### 5. Throttle replacement If the throttle is confirmed faulty, CEMOTO supplies replacement thumb and twist throttles for the D-series and the eBike range. Confirm the correct part for your model before ordering — see [Spare Parts & Compatibility](https://wiki.cemotoride.com/link/382). --- ## Symptom: throttle feels too aggressive or too gentle These are tunable parameters, not faults: | Parameter | Function | Range | | --- | --- | --- | | **P11** | Power sensitivity setting | 1–24 | | **P12** | Power start intensity setting | 0–5 | | **P14** | Controller current limit value | 1–20A (default 12A) | Lowering P11, P12 and P14 together produces a noticeably softer, more controllable throttle — useful when a less experienced rider is using the bike. --- ## Symptom: E13 Front Light Error The headlight circuit is reporting a fault. **Check before replacing the headlight:** 1. **Headlight connector.** Unplug and inspect for corrosion, water ingress or bent pins. Reseat firmly. 2. **Wiring run.** Check the harness from the headlight back to the controller for chafing, especially where it passes the steering head. Turning the bars lock to lock is a common cause of a broken wire. 3. **Bulb / LED board.** If the connector and wiring are sound, test the light unit. 4. **Earth / ground.** A poor ground can trigger a light fault code as easily as a failed light. **Video:** *E13 Error? Don't Swap the Headlight Yet — Check This First* — see [Technical Guides](https://wiki.cemotoride.com/link/336). D-series models use **dual LED headlights**; the D02 Track ships with a headlight included in the assembly kit and must be installed during assembly. --- ## Symptom: horn not working Note that the **D02 Track ships without a horn** as a deliberate track configuration, and the D02 Classic removes the horn as part of its lower-cost off-road-first specification. Confirm your model is actually equipped with one before diagnosing a fault. If your model does have a horn: 1. **Check the horn button** operates and returns. 2. **Check the horn connector** for corrosion and firm seating. 3. **Check the wiring** to the horn for continuity. 4. **Test the horn directly** against a 12V supply to isolate a failed horn from a switch or wiring fault. **Video:** *Horn Not Working — Check These Before Replacing Parts* — see [Technical Guides](https://wiki.cemotoride.com/link/336). --- ## Symptom: cruise control will not engage, or will not disengage Check parameter **P17**: - `0` — No cruise control - `1` — Cruise control enabled (optional) **To engage:** long press while stationary enters **6 km/h cruise** mode. Long press while riding enters **real-time cruise** mode. **To cancel:** long press again. Cruise also cancels when the brake is applied. If cruise will not disengage with the brake, treat it as a brake sensor fault — see [Brakes](https://wiki.cemotoride.com/link/328) and error **E02**. --- ## Symptom: brakes cut power but the lever feels wrong The brake lever is an electrical control as well as a hydraulic one. If the brake signal is stuck on, the controller will refuse to drive. See [Brakes](https://wiki.cemotoride.com/link/328). --- ## Related pages - [Display & Settings](https://wiki.cemotoride.com/link/330) - [Display & Error Codes](https://wiki.cemotoride.com/link/332) - [Power & Start-Up Faults](https://wiki.cemotoride.com/link/334) - [Spare Parts & Compatibility](https://wiki.cemotoride.com/link/382) - [Technical Guides](https://wiki.cemotoride.com/link/336)