OBD LensEnhanced OBD2 PIDs: Mode 22 Explained
Standard PIDs (Service $01) use SAE J1979 definitions; each vehicle supports a subset. Enhanced PIDs are manufacturer-specific signals, often read using Service $22, including UDS ReadDataByIdentifier (ISO 14229). Identifiers, scaling and availability depend on the make, model, ECU and software. Always confirm the actual ECU response.
OBD-II PIDs overview provides an overview; ParsePID project documents manufacturer-specific Mode 22 exploration.
| Question | Standard | Enhanced |
|---|---|---|
| Defined by | SAE J1979 | Manufacturer / ECU implementation |
| Request service | Typically $01 | Often $22; other protocols also exist |
| Same on every car? | Shared meanings; supported subset varies | No; identifiers and scaling vary |
| Examples | Engine speed, fuel trim | Transmission fluid temperature; see exact profile definitions |
How an enhanced request works
For UDS ReadDataByIdentifier, $22 is followed by a two-byte data identifier (DID). Physical addressing targets a particular module; functional addressing targets a diagnostic function that may reach multiple modules. Transport, addressing and session requirements depend on the ECU. See OBD-II PIDs overview and community-documented Ford Transit examples; community examples are not universal OEM specifications.
Why a value can be wrong
The wrong module, formula or ECU software can produce a plausible but incorrect value. Match the exact profile and confirm actual ECU response, returned unit and decoding before interpretation. No data is not zero. A catalog entry does not establish physical-vehicle validation.
Published enhanced coverage
54,260 canonical enhanced-PID URLs are in the committed sitemap; 54,261 meaning pages are recorded in the public content pack, across 100 catalog brands with enhanced coverage. Definition variants are distinct from page counts. These are library counts, not verified cars or supported readings on every ECU.
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Use readings alongside trouble codes
For P0171, compare short-term fuel trim and long-term fuel trim in the vehicle’s operating context. Transmission-fluid temperature is present in enhanced definitions; choose the exact profile-linked temperature signal when investigating transmission codes. A reading alone does not identify a failed component.
Frequently asked questions
Can a cheap ELM327 read enhanced PIDs?
Price alone does not establish capability. The adapter must support the vehicle’s transport and addressing, and the app needs the correct request and decoder. Confirm compatibility with the exact ECU.
Are Mode 22 and UDS $22 the same?
They share the service number commonly used for manufacturer-specific reads. UDS $22 is ReadDataByIdentifier; an older or vendor-specific Mode 22 implementation must not be assumed to share every UDS rule or identifier.
Why does my scanner show no data for a PID?
The ECU may not support that identifier, the wrong module or profile may be selected, or protocol, session and operating conditions may not be satisfied. Verify the response and manufacturer information; unavailable is not zero.