0x22Conditions Not Correct
The ECU cannot execute the requested service under current operating conditions; verify vehicle state, session, and service prerequisites.
UDS Diagnostic Tool
UDS NRC Decoder
Decode common UDS negative response codes and get a concise explanation of what the response means and what to check next.
- Domain
- Vehicle Diagnostics
- Protocol
- UDS
- Execution
- Local deterministic lookup
Interactive utility
Decode a negative response code
Enter the negative response code byte from a UDS response. The decoder uses a curated deterministic mapping in code and never guesses a meaning for unsupported values. The current dataset covers a useful subset of common standardized NRCs and is not exhaustive.
Ready
Enter an NRC byte to inspect it
The decoder reads hexadecimal values such as 22, 0x22, or 0X22.
Common codes
Curated common NRC subset; not an exhaustive ISO 14229 or OEM-specific reference.
Three-step lookup
How to use the decoder
- 01
Enter the NRC byte
Enter the hexadecimal NRC returned in the UDS negative response, with or without the 0x prefix.
- 02
Decode the value
Submit the byte to normalize it and look for an exact match in the curated local dataset.
- 03
Review the next checks
Use the meaning, category, and suggested engineering checks to continue the diagnostic investigation.
Examples
Common lookup patterns
31Request Out of Range
The request contains a parameter or identifier outside the range supported in the current context; compare it with the ECU diagnostic definition.
0X78Response Pending
The ECU accepted the request but needs more time to finish; keep the diagnostic transaction active and apply the configured response timing.
Protocol context
Technical notes
- A UDS negative response normally contains the negative-response service identifier, the requested service identifier, and the negative response code byte.
- The NRC describes why the ECU could not provide the expected positive response; it is not a Diagnostic Trouble Code.
- OEM-specific behavior and values outside this curated subset should be checked against the applicable ISO 14229 edition and project diagnostic documentation.
FAQ
Negative response code questions
- Is a UDS NRC the same as a DTC?
- No. An NRC explains why a diagnostic request did not receive the expected positive response. A DTC records a detected fault condition maintained by ECU diagnostic software.
- Does the decoder include every possible NRC?
- No. It intentionally supports a curated subset of common codes. A syntactically valid but unsupported byte is reported as not included instead of being assigned a guessed meaning.
- Can I enter the code without the 0x prefix?
- Yes. Inputs such as 22, 0x22, and 0X22 are treated as hexadecimal. The field accepts a single byte from 00 through FF.
Diagnostic support
Need help investigating the response behind the code?
If the NRC appears inside a larger session, transport, timing, or ECU-state issue, I can help analyze the diagnostic sequence and supporting traces.