The PACCAR MX P112D page of the 2013 PACCAR MX Diagnostic Service Manual is the manufacturer reference for diagnostic trouble code P112D, described in the manual as “CAN communication – Message (AT1FC1) rate too low from emission system”. It is a 4-page PDF section covering CAN communication diagnostics on EPA2013 PACCAR MX engines, and it keeps the same layout as every other code page in that manual.
Document details and coverage
| Brand | PACCAR |
| Model coverage | PACCAR MX engines, EPA2013 emissions |
| System group | DTCs / MX Engines (EPA2013) |
| Source publication | 2013 PACCAR MX Diagnostic Service Manual |
| Fault code | P112D |
| Subject | CAN communication |
| Pages | 4 |
| File size | 0.6 MB |
| Format | |
| Language | English |
What PACCAR MX P112D means
The manual files P112D as a 1 trip MIL code with 3 drive cycle recovery, readiness group None and freeze frame type Generic. The diagnostic runs continuously when the ignition is on. The code sets when CAN command message AT1FC1 is missing for more than 1.5 seconds, and it changes to inactive as soon as the error is no longer detected.
Possible causes and technical data
- Breakdown in communication in the CAN network
- Open circuit, short circuit to ground, or short circuit to supply in the CAN network wiring
Because the manual treats this as a network fault rather than a component fault, the technical data section points the technician at the CAN wiring instead of a single sensor. The page then runs 4 numbered troubleshooting steps, each with its own step ID, starting from a visual inspection of connectors and harness with the ignition off. The manual warns against back probing, notes that disconnecting the EAS connectors during troubleshooting produces multiple errors, and reminds the technician to exit the fault code menu in DAVIE and rerun the test before judging whether anything changed.
Who needs this PACCAR MX P112D manual page
Heavy-duty technicians, fleet shops and independent workshops diagnosing Kenworth and Peterbilt trucks with EPA2013 PACCAR MX engines use this page to confirm what the ECU actually measured before parts are ordered. For engine literature, dealer locations and support contacts beyond this single code, start at the PACCAR corporate website.
The complete PACCAR MX P112D extract from the 2013 PACCAR MX Diagnostic Service Manual is filed in the DiagTechPro manuals library, where the 4-page PDF can be viewed or downloaded with a free account.
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