Service Interaction Protocol
ECU Reset
State Impact: Hard Reset (0x01) and Key Off/On Reset (0x02) always revert the ECU to Default Session (0x01) and lock Security Access. Plan workflow accordingly.
Service Purpose
“The ECU Reset service is used to request the server to perform a reset. The server shall simulate the reset condition requested by the sub-function parameter.”
Message Structure
ECU Reset requests are two-byte frames containing the SID and the reset type sub-function. Try toggling between request (TX), response (RX), and split views, filter by semantic type, inspect byte field definitions, explore alternative values, and export code snippets:
◆ PROTOCOL ANATOMY
0x11 ECU RESET
0x11 RESPONSE
Reset Types (Sub-Functions)
0x01FULL_CYCLESimulates a complete power cycle. Initializes both hardware and software layers. All volatile memory is cleared. ECU returns to Default Session.
Request
0x02IGNITION_CYCLESimulates an ignition key cycle. Gentler than Hard Reset — activates newly written configuration parameters without full hardware reinit.
Request
0x03APP_RESTARTRestarts the application software only. Hardware remains live. Fastest reset type — suitable for app hang recovery and quick test resets.
Request
0x04REQUIRES_SECURITYConfigures ECU for rapid power-down mode, bypassing normal shutdown sequences. Used in EOL testing and power management validation.
Request
0x05REQUIRES_SECURITYRestores normal shutdown behavior after rapid power-down mode was activated. Always paired with subfunction 0x04.
Request
Request Processing & Validation
The ECU processes reset requests through a sequential 5-step validation pipeline. Each gate failure returns a specific NRC. All five must pass before the positive response is sent and reset executes.
51 0X, drains communication, then executes the requested reset type. Comm stack goes offline during reset.Click any step to expand validation logic.
Service Dependencies & Interactions
0x11 restarts ECU hardware/software, terminating active sessions and relocking security. Select a node to inspect interactions.
Reset Type vs. Session Matrix
Session availability determines which reset types are accessible. Select a session below to filter the supported reset types and expand any row for detailed requirements.
ECU Reset Session & Security Matrix
Which reset sub-functions execute in each diagnostic session, and security requirements. Select a row for details.
| Reset Sub-function | DEFAULT 0x01 | EXTENDED 0x03 | PROGRAMMING 0x02 | SAFETY 0x04 | Security |
|---|---|---|---|---|---|
| ~ | ✓ | ✓ | ~ | — | |
| ~ | ✓ | ✓ | ✗ | — | |
| ✓ | ✓ | ✓ | ~ | — | |
| ✗ | ✓ | ✗ | ✗ | Level 1 | |
| ✗ | ✓ | ✗ | ✗ | — |
Suppress Positive Response (SPRMIB)
RESPONSE_SUPPRESSION_LOGIC
Active Bit 7 (0x80) detection. When present in the sub-function byte, the ECU enters Silent Mode for positive responses, optimizing packet throughput.
!Critical: NRC 0x7F bypasses suppression logic and will always broadcast.
ECU State Machine Phases
From request receipt to ECU back online — eight discrete phases. Select a reset type, press Simulate to animate through all states, or click any state node to inspect it directly.
—ECU is fully operational on the diagnostic bus. Ready to receive service requests. Session and security state as last configured.
Press Simulate to animate through all phases, or click any state to inspect it.
Communication State Transitions During Reset
The communication bus goes through four states during a reset. Select a reset type to compare offline durations — the key variable determining how long the tester must wait.
Tester: Do not send requests during COMM_OFFLINE. The ECU cannot respond. Wait until it comes back online, then verify Default Session before any elevated operations.
Select reset type to compare offline durations. Click phase to expand.
Security State Behavior
Security requirements vary by subfunction and OEM implementation. Subfunctions 0x04/0x05 universally require security unlock. Others are implementation-dependent.
Hard Reset
Vendor-configurable. Some ECUs require security unlock to prevent unauthorized bus disruption during critical vehicle operation, while others allow free resets for debug purposes.
Standard reset types (0x01 Hard, 0x02 KeyOffOn, 0x03 Soft) are permitted when locked in authorized sessions. Privileged power modes (0x04 EnableRapidPowerDown) return NRC 0x33 (SecurityAccessDenied) if issued while locked.
All supported reset subfunctions, including rapid power-down modes, are fully executable.
Triggered when this service or requested resource requires an active security unlock that has not been granted.
Triggered during unlock attempts if the calculated key fails ECU cryptographic verification.
Enforced delay lockout if the maximum number of failed key submissions (typically 3) has been exceeded.
Complete Workflow Examples
Three canonical workflows covering the most common ECU Reset use cases. Select a workflow and run the animated step sequence to trace the full hex exchange.
Full software reprogramming sequence. Uses Hard Reset to apply new firmware after programming session completes all data transfer blocks.
10 02Enter Programming SessionActivates bootloader, enables flash services
27 01Request SeedSecurity level for programming unlock
27 02 <key>Send Computed KeyUnlock security for erase/write ops
28 03Disable Non-Diagnostic CommsIsolate ECU during flash
34 00 44 <addr> <len>Request DownloadDeclare memory write range
36 01..NN <block>Transfer Data BlocksAll firmware blocks sequentially
37Transfer ExitFinalize and checksum verify
11 01Hard Reset ECUApply new firmware via power cycle
—Wait for ECU OnlineTypically 5–10 seconds offline
10 01Verify Default SessionConfirm ECU back online, security locked
Hard Reset Execution
6 stepsTroubleshooting & Common Issues
Work through the diagnostic checklist when a reset request fails or behaves unexpectedly. The issue cards below map NRC codes to root causes and fixes.
Click any issue card to reveal cause and fix.
Negative Response Codes
EXCEPTION_MATRIX_V3
The requested reset type is not implemented by this ECU. Value is outside 0x01–0x05 or unsupported OEM code.
This negative response indicates a rejection while processing the ECU Reset (SID 0x11) request. Verify preconditions, session levels, and message formatting per ISO 14229.
Quick Reference & Best Practices
At-a-glance reference for all five reset subfunctions with timing, state impact, and use cases. Use the checklist to verify compliance before and after reset operations.
Volatile cleared · NVM preserved · DTC preserved