CAT Engine 58569 Fault Code: SAE J1939 Data Link #3:Abnormal Update Rate
Also called J1939 Network #3 : Abnormal Update Rate, SAE J1939 Data Link #3 - Abnormal Update Rate
SAE J1939 Data Link #3:Abnormal Update Rate · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 58569, SPN 1235 FMI 9, means the ECM has lost normal communication with one or more devices on the J1939 data link #3. On C13, C15, and C18 engines this can prevent the engine from starting, and Caterpillar's own notes for this code state that condition directly.
High severity. Caterpillar lists a specific condition tied to this code: the engine will not start. That alone makes this a stop-and-diagnose issue rather than something to run through a shift, even though the root cause is often a wiring or resistor problem rather than internal engine damage.
What does CAT Engine error code 58569 mean?
SPN 1235 FMI 9 points at the J1939 data link, the network that lets the engine ECM (referred to as ECM 1) talk to other electronic modules on the machine, such as a second ECM (ECM 2), a DCU, a PETU (Pump, Electronics, and Tank Unit), a soot sensor, or a NOx sensor. FMI 9 specifically means an abnormal update rate: messages that should arrive on a regular schedule are missing, late, or stopped.
Caterpillar's diagnostic text says this plainly: communication has been lost to one or more devices on the data link. If more than one device has dropped off, that points strongly toward a shared problem such as the data link wiring itself, its power feed, or its ground circuit, rather than one bad sensor.
Because engine control, emissions components, and other modules rely on this network to share data, a broken or noisy data link can stop the engine from starting at all. That is listed directly as one of the conditions this code generates.
Common causes of 58569
- ECM 1 unable to communicate on the data link at all
- ECM 1 unable to communicate specifically with ECM 2 on the data link
- ECM 1 unable to obtain a network address on the data link
- ECM 1 detects a failed address claim from ECM 2 on the data link
- ECM 1 not receiving all expected parameters from ECM 2 on the data link
- A PETU, soot sensor, or NOx sensor incorrectly starting or stopping its data transmission
- Damaged connectors or wiring on the data link harness
- A general problem with the wiring harness
- A faulty terminating resistor on the data link
- Wrong component installed, or a component that needs correct configuration
- A component that needs to be reflashed with the correct flash file
- Faulty ECM 2
- Faulty DCU (Device Control Unit)
How to troubleshoot CAT Engine 58569: first checks
- Inspect all data link connectors for corrosion, bent pins, moisture, or loose fit. Clean and reseat as needed with the engine off.
- Visually trace the harness for chafing, pinches, or damage, especially near frame flex points and clamps.
- Check the terminating resistor(s) on the data link circuit. A failed resistor is listed repeatedly as a cause and is a common quick check before chasing wiring further.
- Confirm which modules are missing from the network. If several devices are silent at once, focus on shared wiring, power, or ground rather than one sensor.
- Verify that components like ECM 2, the DCU, PETU, soot sensor, or NOx sensor are the correct part for the application and are configured correctly, and that flash files are current.
- If a single component is confirmed bad by testing, replace that failed component rather than guessing at the harness first.
How the code clears
No separate clearing step is listed for this code beyond fixing the root cause. Once the failed component, connector, wiring, or terminating resistor is repaired or replaced and the network is communicating normally again, the code should stop being active. Caterpillar's notes say to replace the failed component or repair/replace parts as necessary, then confirm the engine starts and stays connected on the data link.
Affected models and serial ranges
58569 appears in our records across 3 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C13 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C18 | Serial range not listed in source records |
Frequently asked questions
What does CAT fault code 58569 mean?
It means SPN 1235 FMI 9, an abnormal update rate on J1939 data link #3. The engine ECM has lost normal, on-schedule communication with one or more other modules on the network.
Will fault code 58569 stop my engine from starting?
Yes, it can. Caterpillar lists 'the engine will not start' as one of the direct conditions generated by this code, so it should be treated as more than a nuisance fault.
What usually causes this data link fault?
Common causes include damaged connectors or wiring, a faulty terminating resistor, a module like ECM 2, PETU, soot sensor, NOx sensor, or DCU that stopped communicating correctly, or a component that is the wrong part, misconfigured, or needs a flash update.
Is this a sensor problem or a wiring problem?
It can be either. Caterpillar notes that if multiple devices are not communicating, the problem is more likely shared wiring, power, or ground rather than a single sensor. If only one device is affected, focus on that specific component and its connectors.
Which engines use this code?
This code applies to CAT C13, C15, and C18 engines that use the J1939 data link for communication between the ECM and other modules.
Where should I start diagnosing SPN 1235 FMI 9?
Start with a visual check of connectors and harness for damage, then check the terminating resistor, since a faulty resistor is listed multiple times as a cause. From there, identify exactly which modules are dropping off the network before replacing parts.