ABS Wheel Speed Sensor Circuit Open (Front Axle)
The VOLVO-MACK-MID136-PID789-FMI5 (Volvo/Mack D/MP Series) diesel fault code means: ABS Wheel Speed Sensor Circuit Open (Front Axle). This is a moderate severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $150-$500
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View pilot availability →What Are the Symptoms of VOLVO-MACK-MID136-PID789-FMI5?
- ABS warning lamp illuminated
- Possible ATC (traction control) disabled
- ABS disabled during the affected wheel
- Check Engine Light may also set from multiplexing
What Causes VOLVO-MACK-MID136-PID789-FMI5? (Most Likely First)
- Failed ABS wheel speed sensor Likely
- Harness damage at wheel end or frame crossover Likely
- Tone ring contaminated with metal debris Possible
- Incorrect sensor air gap from loose mounting Possible
- ABS ECU fault Less Likely
Can I Still Drive with VOLVO-MACK-MID136-PID789-FMI5?
Yes, but fix soon. VOLVO-MACK-MID136-PID789-FMI5 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.
Frequently Asked Questions
What does Volvo/Mack code SPN 789 FMI 5 (MID 136) mean?
Volvo/Mack SPN 789 FMI 5, reported by the ABS module (MID 136), is a moderate-severity diagnostic trouble code set on D11/MP7, D13/MP8, and D16/MP10 diesel engines in Volvo VNL/VNR and Mack Anthem/Pinnacle/Granite/Titan trucks. On trucks reporting via the older J1587 protocol, this same fault appears as MID 136 SID 1 FMI 5. It indicates a fault in the ABS wheel speed sensor system and should be read with Volvo Premium Tech Tool (PTT) or Mack Guided Diagnostics.
Can I drive a Volvo or Mack truck with this code?
Yes, you can drive short-term. The foundation (service) brakes work normally, but ABS and traction control are disabled or degraded on the affected channel, so the wheel can lock under hard braking on slick surfaces. The ABS lamp will stay on until the open circuit is repaired. Get it diagnosed promptly.
How much does it cost to fix this code?
Typical repair falls in the range $150-$500. A wheel speed sensor is $30-$100 in parts plus an hour or two of labor; harness repairs at the axle flex point or frame crossover run higher. No ECU programming is needed for a sensor swap -- after repair, driving faster than roughly 5 mph confirms the fault clears.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose VOLVO-MACK-MID136-PID789-FMI5?
Connect Volvo PTT or Mack Guided Diagnostics (ABS module, MID 136) and verify SPN 789 FMI 5 active; read wheel speed live data.
Inspect sensor mounting and air gap; clean tone ring of metallic debris.
Measure sensor resistance at the harness (spec typically 1000-2500 ohms).
Inspect harness routing for chafe at axle flex point and frame crossover.
After repair, road-test above 5 mph to verify fault clears and ABS lamp goes out.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J1939-73Application Layer: Diagnostics (defines the SPN/FMI fault-identifier framework)
Which Vehicles Commonly Get VOLVO-MACK-MID136-PID789-FMI5?
- Volvo VNL 760/860 with D13
- Volvo VNR 640 with D11/D13
- Mack Anthem with MP8
- Mack Pinnacle with MP7/MP8
- Mack Granite with MP7/MP8
- Mack Titan with MP10
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