Knowledge Base
Last Updated: 2026-07-30
A 0x8002 acknowledgement proves that the DoIP entity accepted the diagnostic message. It does not prove the request reached a vehicle bus or that an ECU received or answered it.
Interpret the retained observation before assigning a diagnostic conclusion.
Observed
The retained tester-side windows show Routing Activation, DoIP diagnostic-message acknowledgement, and either a bounded absence of final UDS response or a separate positive-response control.
Supported interpretation
The DoIP entity accepted the diagnostic message; the retained window distinguishes an observed final UDS response from its bounded absence.
Not established
Gateway internal processing, bus forwarding, ECU receipt, ECU execution, a response outside the retained window, and root cause are not established.
Recommended next check
Collect synchronized gateway and bus-side evidence for the same request window before locating a downstream fault.
Read this as a role-based swimlane: it shows observed request/response order, not an unproven causal chain.
Observed: The retained tester-side windows show Routing Activation, DoIP diagnostic-message acknowledgement, and either a bounded absence of final UDS response or a separate positive-response control.
Not established: Gateway internal processing, bus forwarding, ECU receipt, ECU execution, a response outside the retained window, and root cause are not established.
Next check: Collect synchronized gateway and bus-side evidence for the same request window before locating a downstream fault.
Tester
Gateway / ECU
Evidence boundary
RA 0x10 and diagnostic request
0x8002 acknowledgement
Final UDS response observed or absent in window
No. It confirms acceptance at the DoIP entity boundary.
These summaries group approved records without extending what any individual window establishes.
Problem signal: A tool label of ECU no response is treated as a target-side diagnosis.
Observed: The DoIP entity acknowledges the diagnostic message, while no matching final UDS response is observed before the retained window ends.
Supported interpretation: The observation boundary is after DoIP acceptance and before a proven final outcome.
Not established: Bus forwarding, ECU receipt, ECU execution, or a target-side fault.
Next check: Collect synchronized gateway and bus-side evidence for the same request.
Evidence IDs: EVID-RA-ACK-NO-FINAL-UDS-01
Problem signal: Acknowledgement is assumed to determine the same downstream result every time.
Observed: A comparable retained control has DoIP acknowledgement followed by a positive final UDS response.
Supported interpretation: The two retained windows have different observed final outcomes.
Not established: A common root cause, parallel-mode behavior, or a forwarding mechanism.
Next check: Compare correlated request, transport, gateway, and bus-side evidence.
Evidence IDs: EVID-RA-ACK-FINAL-UDS-POSITIVE-CONTROL-01
Best when the tool reports no ECU response after a Routing Activation Response code 0x10.
Each example identifies whether it is a controlled simulator observation or a redacted field-evidence window. The evidence record bounds what the sequence can and cannot establish.
Parallel run
Evidence reference: EVID-RA-ACK-NO-FINAL-UDS-01
The DoIP entity acknowledges two comparable diagnostic attempts, while no matching final UDS response is observed before the retained window ends.
Evidence signals
Real Timeline
The boundary is after DoIP acceptance, not conclusively at the ECU.
Serial positive control
Evidence reference: EVID-RA-ACK-FINAL-UDS-POSITIVE-CONTROL-01
A serial control receives the DoIP acknowledgement and a final positive UDS response shortly afterward.
Evidence signals
Real Timeline
It prevents treating every acknowledged request as an inevitable no-response case.
These packet-level checkpoints are the smallest proof units behind the article narrative.
RA response
DoIP entity -> tester
0x0006 code 0x10.
Routing control path is active.
Diagnostic acknowledgement
DoIP entity -> tester
0x8002 / code 0x00.
Entity accepted the diagnostic message.
Observation horizon
downstream path
Final UDS response appears in the control but not the parallel retained window.
Requires gateway/bus evidence for further localization.
This is the condensed engineering verdict the analyzer would put in front of the operator.
No final UDS response observed within the evidence window after DoIP acceptance.
Do not claim forwarding, ECU receipt, or root cause without synchronized downstream evidence.
These are cases where the tool symptom can point in the wrong direction unless the packet timeline is checked.
Symptom: The tool says ECU no response.
Packet truth: Only the absence of a final UDS response in the retained tester-side window is proven.
Risk: The fault is over-located to the ECU.
Symptom: 0x8002 is treated as bus forwarding confirmation.
Packet truth: It is an entity-boundary acknowledgement.
Risk: Gateway-side and bus-side checks are skipped.
Use this order in real troubleshooting so packet evidence narrows the branch before repair effort expands.
These are the interpretation traps that real packet evidence helps avoid.
Say ‘no final UDS response observed within the evidence window’, not ‘the ECU did not respond’.
Exclude capture loss, reassembly errors, and response traffic outside the retained window before using this diagnosis.
Compare an equivalent serial run that has the same DoIP acknowledgement followed by a final positive UDS response.
The comparison is evidence of different observed outcomes, not proof of a single parallel-mode root cause.
It is not located by this evidence alone; synchronized gateway and bus evidence is still required.
Use nearby guides to move from protocol filtering to root-cause troubleshooting without leaving the knowledge base.