RAM 2500 OBD-II Diagnostic Guide
Comprehensive diagnostic trouble code telemetry, sensor voltage thresholds, and step-by-step repair manuals for RAM 2500 models equipped with 6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP).
RAM 2500 Problem & Reliability Intelligence by Year
Top Check Engine Trouble Codes for RAM 2500
P0401 on RAM 2500: Diagnosis & Fix
Troubleshooting procedure for P0401: P0401: Exhaust Gas Recirculation (EGR) Flow Insufficient specifically affecting RAM 2500 (6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)).
P0299 on RAM 2500: Diagnosis & Fix
Troubleshooting procedure for P0299: P0299: Turbocharger / Supercharger Underboost Condition specifically affecting RAM 2500 (6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)).
P0520 on RAM 2500: Diagnosis & Fix
Troubleshooting procedure for P0520: P0520: Engine Oil Pressure Sensor/Switch Circuit Malfunction specifically affecting RAM 2500 (6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)).
P0300 on RAM 2500: Diagnosis & Fix
Troubleshooting procedure for P0300: P0300: Random or Multiple Cylinder Misfire Detected specifically affecting RAM 2500 (6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)).
P0171 on RAM 2500: Diagnosis & Fix
Troubleshooting procedure for P0171: P0171: System Too Lean (Bank 1) specifically affecting RAM 2500 (6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)).
Looking for another fault code on your RAM 2500?
Search our comprehensive 200+ SAE J1979 master OBD-II directory for Powertrain (P), Body (B), Chassis (C), and Network (U) diagnostic codes.
Frequently Asked Questions
Where is the OBD-II diagnostic port located on the RAM 2500?
On the RAM 2500 (2020–2026), the standard 16-pin DLC port is located: Driver footwell below steering column near parking brake. It supports SAE J1979 / ISO 15765-4 CAN protocols for all handheld OBD-II code readers.
What are the most common Check Engine fault codes on the RAM 2500?
The most frequently logged trouble codes on the RAM 2500 (6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)) include P0401, P0299, P0520, P0300.
How does an onboard diagnostic scan communicate with the RAM 2500?
Connecting an OBD-II scanner to the RAM 2500's 16-pin DLC port establishes a high-speed CAN link (ISO 15765-4) with the ECM/PCM. It interrogates SAE J1979 Modes $01 through $0A for active DTCs, freeze-frame sensor telemetry, and oxygen sensor readiness monitors.