Diesel Technicians & Diesel Engine Repair in Anaheim, CA
McPeek’s Chrysler Dodge Jeep Ram of Anaheim services diesel engines at 1221 S Auto Center Dr., Anaheim, CA 92806 — the 6.7L Cummins Turbo Diesel (RAM 2500–5500) and the 3.0L EcoDiesel V6 (RAM 1500, Jeep Grand Cherokee, Wrangler, Gladiator) — using factory Mopar diagnostics and Mopar/Cummins parts. Open Mon–Fri 7 AM–7 PM, Sat 8 AM–5 PM.
Diesel service at a glance
What we fix
DEF & SCR systems, DPF regeneration and cleaning, turbochargers, high-pressure fuel systems and injectors, glow plugs, EGR coolers, exhaust brakes, heavy-duty transmissions, and full factory diagnostics.
Who we serve
Owner-operators, contractors, RV and toy-hauler owners, and commercial and municipal fleets of any size across Orange County, the Inland Empire, and Los Angeles County.
Why a dealer
Factory-trained technicians, dealer-level scan tooling, Mopar and Cummins parts, warranty and recall repairs performed in-house, and California emissions compliance handled correctly.
Amenities
Express Lane, loaner vehicles, early-bird drop-off, Saturday hours, Spanish-speaking staff, and free Wi-Fi.
Diesel engines we service
| Engine | Vehicles | Output |
|---|---|---|
| 6.7L Cummins Turbo Diesel (2025+ High-Output) | RAM 2500 / 3500 | 430 hp / 1,075 lb-ft · TorqueFlite HD 8-speed |
| 6.7L Cummins Turbo Diesel (Chassis Cab) | RAM 4500 / 5500 | 360 hp / 800 lb-ft · TorqueFlite HD 8-speed |
| 6.7L Cummins Turbo Diesel (2024 & earlier) | RAM 2500 / 3500 | 370–420 hp / 850–1,075 lb-ft · 68RFE or Aisin 6-speed |
| 3.0L EcoDiesel V6 | RAM 1500 (through 2023) · Jeep Wrangler & Gladiator (2020+) · Jeep Grand Cherokee | 260 hp / up to 480 lb-ft |
The 2025 Cummins redesign matters for service: a new high-pressure fuel system, new variable-geometry turbo, updated glow plugs, relocated filters, and a switch to the TorqueFlite HD 8-speed. A 2024 truck and a 2026 truck are meaningfully different machines to service — our technicians are trained on both.
Note: the current RAM ProMaster is gas (3.6L Pentastar V6) or electric, not diesel — we service those in the same commercial department, so a mixed fleet can be handled at one location.
Factory maintenance intervals
These are the factory-published intervals McPeek’s works to. Severe duty — heavy towing, fleet use, extended idling — shortens several of them.
| Service item | 6.7L Cummins | 3.0L EcoDiesel |
|---|---|---|
| Engine oil & filter | Per oil indicator; never over 15,000 mi / 12 mo (2024 & earlier: or 500 engine hours) | Per oil indicator; never over 10,000 mi / 12 mo / 350 hours |
| Fuel filters | Both (3-micron chassis + 5-micron engine) every 15,000 mi | Drain & replace at every oil change |
| Oil capacity & spec | 12 qt · API CK-4 heavy-duty diesel oil | 8.5 qt · 5W-40 synthetic |
| DEF check | Every 7,500 mi or 6 months | |
| Engine air filter | Inspect at 15,000 mi; replace by 30,000 mi | Every 20,000 mi |
| Transmission fluid | 8-speed: 60,000 mi · Aisin: 30,000/60,000 mi · 68RFE: 120,000 mi (60,000 fleet/towing) | — |
| Coolant flush | 10 years or 150,000 mi (OAT formula only — never mix coolant types) | |
EcoDiesel owners: RAM’s manual warns that skipping the fuel filter at an oil change “will result in premature engine wear” that is not covered by the New Vehicle Limited Warranty. It’s one of the few maintenance shortcuts that can void coverage on the failure it causes.
Sources: 2023–2025 RAM Owner’s Manuals (vehicleinfo.mopar.com). Verify against your VIN and model year.
Diesel warning lights, decoded
| Message / light | What it means | What to do |
|---|---|---|
| “Exhaust Filter Nearing Full” | DPF soot at ~70%; the truck needs a regeneration. | Drive at sustained highway speed until it clears. Don’t shut off mid-regeneration. At 90% it takes ~45 minutes of driving. |
| Check engine + reduced power (DPF 100%) | Regeneration is no longer possible; a full DPF can damage the exhaust system. | Bring it in — the filter must be manually cleaned or replaced. |
| Water in Fuel | Water in the separator. At 29,000 psi, water destroys injectors and pumps. | Do not start the engine. Call 714-908-4176 before you drive. |
| DEF warning / “Refill DEF” | Low or poor-quality DEF. An empty tank triggers speed limits, then a no-restart. | Refill with ISO 22241-certified DEF. If the warning persists, the DEF system itself needs diagnosis. |
| Clicking from the DEF system | The dosing module purging DEF — even with the truck off. | Nothing. RAM’s manual confirms this is normal. |
DEF and DPF, in plain English
DEF (diesel exhaust fluid) is ~32.5% urea in deionized water, injected into the exhaust to convert NOx into nitrogen and water vapor. Consumption tracks fuel burned — roughly 2–3% of diesel used — so a truck towing a fifth wheel over the Grapevine refills far more often than a commuter on the 91. Use only DEF certified to ISO 22241; contaminated or farm-grade urea can mean dropping the tank and replacing the pump and sensors.
DPF regeneration is the truck raising exhaust temperature to burn soot out of its particulate filter. Most happen invisibly while you drive. What clogs a DPF: repeated short trips, extended idling, shutting off mid-regeneration, upstream faults (EGR, turbo, injectors), and oil consumption. Stop-and-go Orange County traffic is exactly the duty cycle that prevents regeneration — RAM Chassis Cabs (4500/5500) have an in-cab stationary regeneration, but pickups don’t, so a loaded pickup DPF needs a dealer-level service regeneration or cleaning.
If your truck lives in traffic, tell us. A delivery truck running Anaheim to Santa Ana all day and a weekend tow rig have completely different regeneration profiles — that context changes what we look at.
California diesel rules to know
California’s rules split at 14,000 lb GVWR — confirm yours on the driver’s door-jamb label.
- Smog Check (14,000 lb and under, 1998+): diesel pickups get the OBD inspection — and unlike gas vehicles, new diesels are not exempt. A brand-new diesel RAM 2500 is Smog Check eligible from day one. The visual inspection also verifies every emissions device is present — a deleted truck fails on sight.
- CARB Clean Truck Check (over 14,000 lb): generally applies to RAM 4500/5500 Chassis Cabs and larger. OBD-equipped vehicles currently test twice a year (four times a year starting October 2027), with a $32.13 annual fee. Missing a deadline leads to a DMV registration hold.
- The readiness-monitor trap: clearing codes right before an OBD submission resets the monitors and gets the test rejected. If you have a check-engine light and a deadline coming, repair first, drive enough cycles to set the monitors, then submit — bring it in early, not the week the deadline hits.
Will McPeek’s delete my emissions system?
No. Removing or tuning out DPF, DEF, SCR or EGR equipment is illegal in California (Vehicle Code §27156, penalties up to $37,500 per violation), voids emissions warranty coverage, and fails Smog Check on sight. If you bought a truck a previous owner deleted, we can quote restoring it to certified configuration — the only path back to legal registration, warranty eligibility, and resale value.
Factory diesel warranty coverage
Only a franchised dealer can perform factory warranty, emissions warranty, and recall repairs at no charge to you.
| Coverage | Term |
|---|---|
| 2026 Limited Powertrain Warranty (incl. diesel injection pump & injectors) | 10 years / 100,000 miles (original owner) |
| Cummins Diesel Engine Limited Warranty (2025 MY) | 5 years / 100,000 miles |
| California Emission Warranty — RAM 2500/3500 diesel | 5 yr / 50,000 mi; specified components 7 yr / 70,000 mi |
| California Emission Warranty — RAM 4500/5500 diesel | 5 yr / 110,000 mi; specified components 10 yr / 110,000 mi |
Coverage varies by model year and in-service date — verify your vehicle with our advisors. Every service at McPeek’s is recorded to your VIN in the factory service history, which protects warranty eligibility automatically. Two recalls come up often here: 21V-880 (2019–2020 Cummins high-pressure fuel pump) and 20V-699 (2014–2019 Grand Cherokee EcoDiesel EGR cooler). Recall repairs are free regardless of current owner — check your VIN.
Fleet & commercial diesel service
McPeek’s is the #1 RAM Commercial dealer in California for truck sales (2016–2025), serving everyone from single-truck owner-operators to fleets running hundreds of units — including the Anaheim Fire and Police departments.
- Mobile fleet service — certain maintenance and diagnostics come to your yard.
- Hour-based scheduling — the Cummins 500-engine-hour oil clause catches trucks that idle on job sites; we track hours, not just miles.
- Clean Truck Check support — including getting readiness monitors set before a submission window.
- Upfit-aware service — service bodies, stake beds, and hoists; we sell and build these trucks, so the shop is set up for them.
What to expect
- Book it — online or at 714-908-4176. Tell us how the truck is actually used; towing weight and idle hours change the diagnosis.
- Factory diagnosis — all modules scanned, live data reviewed, checked against current service bulletins and calibrations for your VIN.
- Estimate before work starts — findings, recommended repair, and what warranty covers.
- Repair & verify — Mopar/Cummins parts to factory spec, road-tested, fault confirmed cleared (not just erased), and recorded to your factory service history.
Serving Orange County, the Inland Empire & Los Angeles
We’re in the Anaheim Auto Center just off the 5, minutes from the 57 and 91 — an easy run from Anaheim, Orange, Santa Ana, Fullerton, Buena Park, Yorba Linda, Irvine and greater Orange County; Corona, Norco, Chino and the Inland Empire; and Whittier, Downey, Long Beach and Los Angeles County. Get directions.
Diesel service FAQ
Can any mechanic work on a diesel?
Any competent shop can change diesel oil, but modern diesel diagnosis requires factory-level scan tooling that reads every module, runs bi-directional tests, initiates service functions like a stationary DPF regeneration, and flashes current calibrations — generic OBD-II scanners can’t. And only a franchised dealer can perform warranty and recall repairs at no charge.
How often should you change the oil on a 6.7L Cummins?
Follow the oil change indicator, and never exceed 15,000 miles or 12 months (2024-and-earlier trucks add a 500-engine-hour limit that catches fleet and heavy-idle trucks). It holds 12 quarts of API CK-4 heavy-duty diesel oil — not passenger-car oil.
Why does diesel service cost more than gas?
Arithmetic, not markup: the Cummins takes 12 quarts of heavy-duty oil versus 7 quarts in the 6.4L HEMI, adds two fuel filters every 15,000 miles the gas truck doesn’t have, and carries a full aftertreatment system (DOC, DPF, SCR, EGR, DEF dosing) with its own sensors, pumps and heaters. What you get back is service life — properly maintained diesels routinely outlast comparable gas engines.
What happens if you run out of DEF?
The truck warns you progressively, then limits speed, and eventually won’t restart on an empty tank — that’s federally mandated behavior, not a fault. Refilling with ISO 22241-certified DEF restores normal operation; if warnings persist afterward, the DEF system itself needs diagnosis.
Can I force a DPF regeneration myself?
RAM Chassis Cabs (4500/5500) have an operator-initiated stationary regeneration in the cluster (in PARK, fuel above 12.5%). Pickups don’t — when a pickup’s DPF is too loaded to regenerate on the road, it needs a dealer-level service regeneration or physical cleaning.
Why is my diesel blowing white or black smoke?
White smoke on a cold start is normal warm-up; persistent white smoke points to glow plugs, injectors, low compression, or coolant entering the combustion chamber. Black smoke means more fuel than the engine can burn — restricted intake, boost leak, sticking turbo, injector or EGR faults — and it also loads the DPF fast, so it tends to bring a second problem with it. Either way, diagnose before it snowballs.
Do diesel trucks need a Smog Check in California?
Yes — 1998-and-newer diesels at 14,000 lb GVWR or under get the OBD inspection, and unlike gas vehicles, new diesels are not exempt. Vehicles over 14,000 lb fall under CARB’s Clean Truck Check program instead.
Do I have to service at a dealer to keep my warranty?
Routine maintenance can legally be done anywhere with parts and fluids meeting factory spec — but warranty and emissions repairs must be done at an authorized dealer to be free, and every service at McPeek’s is recorded to your VIN automatically, which removes any documentation argument.
How much does diesel repair cost?
It depends on the fault and what warranty covers, so we diagnose before quoting: you get the findings, the recommended repair, what’s covered, and an estimate for approval before any work begins. Current offers are on the service specials page.
Book diesel service in Anaheim
A 15,000-mile Cummins service, a DEF fault you’ve been chasing, a DPF that won’t clear, or a fleet due for Clean Truck Check — the diesel team at McPeek’s can take it on.
1221 S Auto Center Dr., Anaheim, CA 92806
Service: 714-908-4176 · Parts: 714-908-9175
Mon–Fri 7:00 AM–7:00 PM · Sat 8:00 AM–5:00 PM · Sun closed
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