JEEP AVENGER MHEV – SUDDEN SHUTDOWN “PRESS BRAKE AND START”: CAUSES, DIAGNOSIS, SOLUTIONS (2025)

Updated September 2025 — by Gianni Tritella. Some owners of Jeep Avenger MHEV (Hybrid 136 e-DCS6, 48V) report the engine suddenly stalling, with the message " Press brake and START " appearing on the display. The car can continue for a short time in electric mode, then slows to a stop. In many cases, a restart or 12V reset allows the vehicle to restart, but does not resolve the cause . Here you will find what to do immediately , step-by-step diagnosis for the workshop, and preventative measures .

Read Also: 2025 ELECTRIC JEEP AVENGER PROBLEMS: REAL DEFECTS, LIMITATIONS, AND ADVICE FROM AN EXPERT PARTS DEALER

⚠️ Typical symptoms

• Sudden shutdown of the combustion engine at constant speed (even on the motorway/city).
• Message on instrument panel: “Press brake and START” ; no other clear warning lights in user memory.
• The vehicle runs for a short time in electric mode (48V) with limited power, then requests a stop.
• After switching off/on again (or resetting the 12V) the car can restart and travel for hundreds of km without immediately repeating the fault.

🔎 Why it happens (explained simply)

The Avenger MHEV uses a 48V system with an electric motor integrated into the gearbox and a 12V network that powers control units and services. If the 12V network experiences a voltage drop (battery, ground, DC-DC), if a control unit restarts for protection , or if there is an "inconsistent" sensor reading (e.g., brake pedal), the ICE is safely shut down and the dashboard prompts a restart with the brake pressed. The electrical system only allows "pulling over."

Most frequent triggers detected in the workshop:

• 12V weak/unstable (EFB/AGM battery not at 100%, oxidized terminals or grounds).
• DC-DC 48V→12V which cannot support the load under certain conditions (peaks/climate/lights/fans).
• IBS (battery sensor) not aligned after replacements/reboots, with “confused” power management.
• Dual-channel brake pedal sensor : plausibility temporarily out of range → restart required.
• Software (ECM/HCU/BCM/Cluster/e-DCS6): logic to be updated according to TSB/network updates.
• More rarely: Intermittent CKP/CMP (rpm/camshaft sensors) or CAN with message losses.

🛑 What to do immediately to be safe (for the driver)

1. Keep calm and pull over safely (emergency lane), turn on your hazard lights.
2. Put the gear lever in P (or N + brake), turn off the ignition, wait 60–90 s , then turn it back on by pressing brake and START.
3. If it starts up again normally, avoid further stress and drive home/workshop.
4. Don't disconnect the battery in traffic. A "12V reset" may restart the vehicle, but it will erase the fault data needed for diagnosis.
5. Write down on a sheet of paper/app: date/time , speed, climate on, 48V SOC (if visible), 12V battery status (if the car shows it).

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🧰 Workshop Diagnostics: Technical Checklist (Avenger MHEV 48V)

1) DTC reading + Freeze-Frame (do not erase immediately)

• ECM (engine), HCU/e-DCS6 (hybrid/gearbox module), DC-DC , BMS 48V , BCM , ABS/ESC , Cluster .
• Note: Engine RPM, Speed, KL30/KL15 Voltage, 12V min recorded, SOC 48V, Brake Pedal Status (A/B Channels), “Engine Stop” Request Status.

2) 12V power supply and grounds

• EFB/AGM battery test with tool (SOH/SOC, internal resistance). Hot target: >12.5 V at rest; running lights + A/C: 13.5–14.7 V stable.
• Check terminals , cable lugs, chassis/engine ground points ; voltage drops < 0.2 V at start-up.
• IBS Reset/Alignment after any interventions.

3) DC-DC and 48V network

• Monitor with a road test: DC-DC current, 12V voltage, 48V SOC, module temperature. Look for drops when using the climate control/fans/degiver.
• Check DC-DC connectors and ground; check for “undervoltage” DTCs in the registers.

4) “Critical” sensors and signals

• Brake pedal (dual channel): consistency and latency (no flapping/noise). If in doubt, replace and repeat adjustments.
• CKP/CMP : Hot signal quality (oscilloscope if available), wiring near the gearbox.
• Check power relays /fuses and panel (oxides/loose terminals).

5) Software and campaigns

• Check campaigns/TSBs on the official portal: ECM, HCU/e-DCS6, BCM, Cluster , DC-DC. Perform updates if available.
• Post-update: clear DTC, basic settings required (throttle/idle, IBS, any HCU procedures), road test with logger.

🧩 Quick decision tree (technical)

1. 12V undervoltage recorded? → Low battery SOH or DC-DC drop → Restore 12V (new battery if necessary), clean grounds, check DC-DC. Re-test.
2. No undervoltage but brake pedal inconsistency? → Replace sensor, check wiring, reset adjustments. Retest.
3. DTC on HCU/e-DCS6 or Cluster related to “Engine Stop request / plausibility” → Update software, redo basic settings, extended test.
4. CKP/CMP intermittents → check with an oscilloscope; replace sensor/wiring if necessary. Retest while hot.
5. No reproducible defects → Update everything, document nominal values, deliver with signed report and follow-up in 1–2 weeks.

🛡 Prevention and best practices

• 12V battery in top condition : short trips/hot weather stress it. Maintain a trickle charge in the garage if you make frequent city trips.
• Avoid electrical retrofits that tax the 12V without adequate power.
• After battery work: align IBS and make the required basic settings.
• In the workshop: one change at a time, value reporting and road tests with logger, not just “open/close DTCs”.

❓ Frequently Asked Questions