Editing Unified Diagnostic Services (section)

== Diagnostic Message ==
There are two types of diagnostic messages transmitted using UDS protocol:

* Request
* Response

=== Request Message ===
Request messages are transmitted by a Client towards one or more Servers.<ref>{{Cite web |last=Dąbrowski |first=Maciej |title=Diagnostic Message (Diagnostic Request) — py-uds documentation |url=https://uds.readthedocs.io/en/stable/pages/knowledge_base/diagnostic_message.html#diagnostic-request |access-date=2025-11-11 |website=uds.readthedocs.io |language=en}}</ref>

Service Identifier (SID) is the first byte in each request message.<ref>{{Cite web |last=Dąbrowski |first=Maciej |title=Diagnostic Service (SID) — py-uds documentation |url=https://uds.readthedocs.io/en/stable/pages/knowledge_base/service.html#request-service-identifier |access-date=2025-11-11 |website=uds.readthedocs.io |language=en}}</ref>

=== Response Message ===
Response messages are transmitted by Servers to a Client.<ref>{{Cite web |last=Dąbrowski |first=Maciej |title=Diagnostic Message (Diagnostic Response) — py-uds documentation |url=https://uds.readthedocs.io/en/stable/pages/knowledge_base/diagnostic_message.html#diagnostic-response |access-date=2025-11-11 |website=uds.readthedocs.io |language=en}}</ref>

The first byte in the response message is usually Response Service Identifier (RSID) value (with the exception of following responses to ReadDataByPeriodicIdentifier service).<ref>{{Cite web |last=Dąbrowski |first=Maciej |title=Diagnostic Service (RSID) — py-uds documentation |url=https://uds.readthedocs.io/en/stable/pages/knowledge_base/service.html#response-service-identifier |access-date=2025-11-11 |website=uds.readthedocs.io |language=en}}</ref><ref name=":0" />

==== Positive Response Message ====
Format of each positive response message is specific for the diagnostic service it relates to.

==== Negative Response Message ====
{| class="wikitable"
|+Negative Response Message format
!Byte
!Value
!Description
|-
|#1
|0x7F
|Negative Response SID
|-
|#2
|SID
|SID value from request message
|-
|#3
|NRC
|reason for the rejection
|}

===== Negative Response Codes =====
Negative Response Codes (NRC in short) carry the information for request message rejection.<ref name=":1">{{Cite web |last=Dąbrowski |first=Maciej |title=Diagnostic Message (Negative Response Codes) — py-uds documentation |url=https://uds.readthedocs.io/en/stable/pages/knowledge_base/diagnostic_message.html#negative-response-code |access-date=2025-11-09 |website=uds.readthedocs.io |language=en}}</ref>
{| class="wikitable"
|+Negative Response Codes<ref name=":1" />
! Value!! Name
|-
| 0x10 || generalReject
|-
| 0x11 || serviceNotSupported
|-
| 0x12 || SubFunctionNotSupported
|-
| 0x13 || incorrectMessageLengthOrInvalidFormat
|-
| 0x14 || responseTooLong
|-
| 0x21 || busyRepeatRequest
|-
| 0x22 || conditionsNotCorrect
|-
| 0x24 || requestSequenceError
|-
| 0x25 || noResponseFromSubnetComponent
|-
| 0x26 || FailurePreventsExecutionOfRequestedAction
|-
| 0x31 || requestOutOfRange
|-
| 0x33 || securityAccessDenied
|-
| 0x34 || authenticationRequired
|-
| 0x35 || invalidKey
|-
| 0x36 || exceedNumberOfAttempts
|-
| 0x37 || requiredTimeDelayNotExpired
|-
| 0x38 || secureDataTransmissionRequired
|-
| 0x39 || secureDataTransmissionNotAllowed
|-
| 0x3A || secureDataVerificationFailed
|-
| 0x50 || Certificate verification failed, Invalid Time Period
|-
| 0x51 || Certificate verification failed, Invalid Signature
|-
| 0x52 || Certificate verification failed, Invalid Chain of Trust
|-
| 0x53 || Certificate verification failed, Invalid Type
|-
| 0x54 || Certificate verification failed, Invalid Format
|-
| 0x55 || Certificate verification failed, Invalid Content
|-
| 0x56 || Certificate verification failed, Invalid Scope
|-
| 0x57 || Certificate verification failed, Invalid Certificate ''(revoked)''
|-
| 0x58 || Ownership verification failed
|-
| 0x59 || Challenge calculation failed
|-
| 0x5A || Setting Access Rights failed
|-
| 0x5B || Session key creation/derivation failed
|-
| 0x5C || Configuration data usage failed
|-
| 0x5D || DeAuthentication failed
|-
| 0x70 || uploadDownloadNotAccepted
|-
| 0x71 || transferDataSuspended
|-
| 0x72 || generalProgrammingFailure
|-
| 0x73 || wrongBlockSequenceCounter
|-
| 0x78 || requestCorrectlyReceived-ResponsePending
|-
| 0x7E || SubFunctionNotSupportedInActiveSession
|-
| 0x7F || serviceNotSupportedInActiveSession
|-
| 0x81 || rpmTooHigh
|-
| 0x82 || rpmTooLow
|-
| 0x83 || engineIsRunning
|-
| 0x84 || engineIsNotRunning
|-
| 0x85 || engineRunTimeTooLow
|-
| 0x86 || temperatureTooHigh
|-
| 0x87 || temperatureTooLow
|-
| 0x88 || vehicleSpeedTooHigh
|-
| 0x89 || vehicleSpeedTooLow
|-
| 0x8A || throttle/PedalTooHigh
|-
| 0x8B || throttle/PedalTooLow
|-
| 0x8C || transmissionRangeNotInNeutral
|-
| 0x8D || transmissionRangeNotInGear
|-
| 0x8F || brakeSwitch(es)NotClosed (Brake Pedal not pressed or not applied)
|-
| 0x90 || shifterLeverNotInPark
|-
| 0x91 || torqueConverterClutchLocked
|-
| 0x92 || voltageTooHigh
|-
| 0x93 || voltageTooLow
|-
| 0x94 || ResourceTemporarilyNotAvailable
|}