Cummins · Truck Modules
Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250)
Cummins engines power more than just Cummins-badged trucks — the ISX15/X15 and CM871/CM2350 ECM platforms show up as the spec’d engine option across Freightliner, Western Star, Peterbilt, Kenworth, and International chassis, alongside Cummins’ own ISL9 and ISB6.7 in medium-duty applications. Cummins ECM/ACM failures are common enough to have well-documented fault code signatures.
- ★ Google reviews
- Component-level repair
- 30-day warranty
- Mail-in across Canada
At a glance
- Service
- Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250)
- Common symptoms
- Fault codes 1117, 111, or 343 logged, Heat-related engine shutdowns, DEF/emissions-related derate or fault codes (e.g. 6254/6255/3712 on ISX/CM2350 engines)
- Turnaround
- Diagnosis first; repairs that need parts ordered typically take 2 weeks to 2 months — we confirm the timeline with your quote
- Warranty
- 30-day warranty after repair
- How
- Mail-in from anywhere in Canada · free quote
What Do the ECM and ACM Control?
The ECM manages fuel injection, timing, and engine performance. The ACM (Aftertreatment Control Module) manages the DEF/SCR emissions system separately. Both report fault codes to the dash and diagnostic tools, and either can fail independently.
Why does the Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250) fail?
Most failures trace back to power supply faults, internal microprocessor failure, and internal hardware failure.
- Power Supply Faults – unstable battery voltage or wiring issues are the leading cause behind Fault Code 1117 (Power Supply Lost With Ignition On), one of the most common CM871/CM2350 codes.
- Internal Microprocessor Failure – Fault Code 111 (ECM Microprocessor Internal Failure) indicates a critical internal fault requiring repair.
- Internal Hardware Failure – Fault Code 343 (ECM Internal Hardware Failure) means the truck should not be operated until the module is repaired.
- Wiring Harness and Connector Faults – often mistaken for ECM failure; should be ruled out before condemning the module.
- Heat and Vibration Fatigue – common on high-mileage highway tractors regardless of chassis brand.
Warning signs of a failing Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250)
The most common signs are fault codes 1117, 111, or 343 logged; heat-related engine shutdowns; and DEF/emissions-related derate or fault codes (e.g. 6254/6255/3712 on ISX/CM2350 engines).
- Fault codes 1117, 111, or 343 logged
- Heat-related engine shutdowns
- DEF/emissions-related derate or fault codes (e.g. 6254/6255/3712 on ISX/CM2350 engines)
- Poor engine performance or reduced power
- Difficulty starting or intermittent no-start
- Scan tool unable to communicate with the ECM or ACM
If you’re seeing any of the above, mail your module in for diagnosis — don’t pay for a full dealer replacement first.
How we repair the Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250)
- Fault code retrieval and diagnostic review
- Bench testing to isolate ECM/ACM failure from wiring, power supply, or connector faults
- Component-level repair of damaged circuits and connectors
- Internal memory/data restoration where applicable
- Final bench validation before return
Why send your Cummins module to ECU Repair Doctor?
- Component-level repair — cheaper and faster than a full ECM/ACM replacement
- Clear timeline after diagnosis — repair time depends on parts
- Mail-in service, anywhere in Canada
- 30-day warranty on every repair
- Serves independent shops and fleets, not just individual owners
Which Cummins models are covered?
- Cummins ISX15 / X15
- Cummins ISL9
- Cummins ISB6.7
- Cummins-powered Freightliner, Western Star, Peterbilt, Kenworth, and International trucks
Modules We Service
- Engine Control Module (ECM) – CM871 / CM2350 / CM2250
- ACM (Aftertreatment Control Module) / DEF Emissions Control Module
Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250): frequently asked questions
What are the symptoms of a failing Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250)?
Common signs include fault codes 1117, 111, or 343 logged; heat-related engine shutdowns; DEF/emissions-related derate or fault codes (e.g. 6254/6255/3712 on ISX/CM2350 engines); poor engine performance or reduced power. If you see these, have the module tested before paying for a dealer replacement.
What causes Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250) failure?
The most common causes are power supply faults; internal microprocessor failure; internal hardware failure; wiring harness and connector faults.
Can the Cummins ECM/ACM Repair (CM871 / CM2350 / CM2250) be repaired instead of replaced?
Yes, in most cases. We repair the original module at the component level, so it keeps its VIN and immobilizer data and goes back in plug-and-play. If it can't be saved, we can clone your data onto a replacement unit.
Which models do you cover?
Cummins ISX15 / X15, Cummins ISL9, Cummins ISB6.7, Cummins-powered Freightliner, Western Star, Peterbilt, Kenworth, and International trucks. Call or text 647-784-9939 if your model isn't listed.
How do I send my module in?
Get a free quote by phone, text or the contact form, then pack the module in an anti-static bag with padding and mail it to 76 Sherry Road, Unit H, Scarborough, ON M1L 2J9. We diagnose it first; repairs that need parts ordered typically take 2 weeks to 2 months, and we confirm the timeline with your quote. Every repair has a 30-day warranty.
Last updated October 2026
Don’t replace your Cummins module — repair it.
Most failed modules can be repaired for a fraction of the dealer replacement price, and come back cloned to your vehicle so there’s no extra programming visit.