The 2019 Ram 3500 with the 6.7L Cummins is a workhorse diesel, but the Aisin AS69RC transmission and emissions components drive most shop visits. Expect transmission-related issues and DEF system headaches as primary concerns on higher-mileage units.
Aisin AS69RC Transmission Overheating and Torque Converter Failure
Common · high severity
Typical onset: 80,000-140,000 mi
Symptoms: Transmission temperature climbing above 220°F under load or towing, Shuddering or slipping during lockup, especially 5th-6th gear, Metal contamination in fluid during service, Check engine light with P0741 or P0748 codes
Fix: Torque converter replacement requires full transmission drop (8-12 hours labor). Often discover damaged transmission cooler or clogged lines during diagnosis—address both or you'll be back in six months. Cooler and lines add 2-3 hours. Flush system completely.
Estimated cost: $3,200-5,800
DEF (Diesel Exhaust Fluid) System Failures—Heater and Quality Sensor
Common · high severity
Typical onset: 60,000-100,000 mi
Symptoms: DEF quality sensor fault codes (P20EE, P20B9), Speed limited to 55 mph with countdown warning on cluster, DEF heater circuit codes in cold climates, Crystallized DEF around tank or injector
Fix: DEF tank assembly replacement is the reliable fix—includes heater, pump, and sensors as one unit (4-6 hours labor, bed removal on some configs). Trying to replace individual sensors rarely lasts. Use only top-tier DEF fluid to prevent repeat failures.
Estimated cost: $1,800-3,200
Transmission Cooler Line Corrosion and Leaks
Occasional · medium severity
Typical onset: 70,000-110,000 mi
Symptoms: Transmission fluid dripping from frame rail area, Low fluid level on dipstick with no visible leak at pan, Rust staining on frame near cooler line routing, Sudden fluid loss after winter salt exposure
Fix: Steel cooler lines rust through at mounting brackets and bends. Replace both lines as a set (3-5 hours), not just the leaker. Aftermarket stainless options available and worth the premium in rust-belt states. Refill and relearn procedure required.
Symptoms: Sudden loss of power, hard start, or no-start, Metallic debris in fuel system, P0087 fuel rail pressure too low code, Rough idle progressing to complete failure
Fix: CP4 pump grenades and sends metal through entire fuel system. Requires pump, both injectors, fuel rails, lines, tank drop and cleaning (20-30 hours). Some shops won't touch it—send to diesel specialist. Fuel contamination is total system kill. Aftermarket CP3 conversion kits exist as preventive measure.
Estimated cost: $8,000-12,000
EGR Cooler Clogging and Failure
Occasional · medium severity
Typical onset: 100,000-160,000 mi
Symptoms: White smoke from exhaust on cold start, Coolant loss with no visible external leaks, P0401 or P0403 EGR flow codes, Overheating under load with normal coolant level
Fix: EGR cooler develops internal leaks or clogs with soot. Replacement involves coolant drain, intake removal (6-9 hours). While you're in there, inspect EGR valve and clean intake—carbon buildup is guaranteed. Delete kits are illegal but widely discussed in diesel communities.
Estimated cost: $1,600-2,800
Shift Cable Bushing Wear and Detachment
Occasional · medium severity
Symptoms: Shifter feels loose or sloppy, Gear indicator doesn't match actual gear position, Inability to shift out of park intermittently, Cable pops off ball stud at transmission
Fix: Plastic bushing at transmission end of shift cable wears and fractures. Cable assembly replacement is 2-3 hours—accessible from underneath. Dorman makes a repair bushing kit for $40 that works temporarily but cable replacement is the proper fix.
Estimated cost: $350-650
Transmission Mounting Bracket Fatigue Cracks
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: Clunking from underneath during acceleration or deceleration, Excessive driveline vibration at highway speeds, Visible cracks in crossmember or mount bracket, Transmission sag visible during inspection
Fix: Factory transmission mount and crossmember crack from torque loads, especially on trucks used for towing. Crossmember and mount replacement is 3-4 hours with exhaust removal. Upgraded aftermarket mounts available—recommended for heavy towing applications.
Estimated cost: $600-1,200
Owner tips
Change transmission fluid every 30,000-40,000 mi if towing regularly—Aisin is sensitive to degraded ATF despite 'lifetime fill' claims
Use only top-tier DEF from high-turnover stations; cheap or old DEF crystallizes and kills the system
Install aftermarket transmission temp gauge if towing—factory gauge reads optimistically
CP4 fuel pump insurance: run diesel additive with lubricity enhancer every tank, consider fuel filtration upgrade
Delete EGR cooler only if operating off-road or farm use—emissions tampering carries federal penalties
Bulletproof Cummins engine paired with problematic transmission and emissions gear—budget $3K-5K reserve for DEF/trans work if buying over 80K miles, but underlying platform is solid for serious towing if maintained.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: High-output AGM battery required for 6.7L Cummins diesel; dual battery system available on some configurations
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Every control module on the 2018-2023 Dodge Ram 3500 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Electric Power Steering Module (EPS)2.5 hr R&Rsecurity gateway +0.8 hr▸ programming details
📍 Integrated with steering column assembly, below instrument panel
🔧 wiTECH 2.0 or Autel MaxiSys Elite/Ultra
⚠️ Requires steering angle sensor calibration and end-stop learning procedure after replacement.
⚠️ Critical security module. Enforces Security Gateway protocol. Replacement requires dealer-level authentication and all modules may need reconfiguration.
Door Module (DDM/PDM)1.2 hr R&Raftermarket tool +0.3 hrwith power windows/locks▸ programming details
📍 Inside door panel, driver and passenger doors
🔧 Autel MaxiSys or wiTECH 2.0
⚠️ Controls window, lock, and mirror functions. Requires window auto-up/down relearn after replacement.
⚠️ Monitors DEF quality and level. Requires system reset after replacement.
Seat Control Module (SCM)0.8 hr R&Rrelearn only +0.2 hrwith power seats and memory▸ programming details
📍 Under driver and passenger seats
🔧 Scan tool with bi-directional control
⚠️ Controls seat position, heating, ventilation, and memory. Requires memory position relearn after replacement.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2019 Dodge Ram 3500 6.7L I6 Cummins Diesel and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.