Symptoms
Symptoms of a DTC P2003 may include:
Decreased fuel economy occurs when the engine management system attempts to increase exhaust gas temperature to burn excess soot in the DPF.
The check engine light will illuminate with code “P2003”. The light may stay on or flash intermittently during DPF regeneration. The engine will be sluggish during acceleration.
Engine oil will show dilution from the ECU’s attempts to raise engine temperature. Some vehicles slightly advance fuel injection timing after top dead center to post-combust a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines DPF regeneration is needed, oil life is significantly shortened.
If the DPF isn’t cleared, the ECU will enter “Limp Home Mode” until the situation is corrected.
Potential Causes
Causes of this DTC may include:
Excessive low-speed operation will trigger this code. Heat in the 500°C to 600°C range is required to burn soot in the DPF. Even with the engine management computer’s efforts, it struggles to generate enough heat to clean the DPF at low RPMs.
- An air leak upstream of the DPF will alter sensor readings resulting in the code
- Faulty computer strategies or components will prevent proper regeneration
- Fuel with high sulfur content quickly clogs the DPF
- Some aftermarket accessories and performance modifications
- Dirty air filter element
- Damaged DPF
Diagnostic Steps
and possible solutions
Solutions are somewhat limited since the DPF isn’t faulty, only temporarily clogged with soot particles. If the light is on and P2003 code is set, use the process of elimination starting with a visual inspection.
Inspect the DPF on bank #2 for loose connections on the engine side where it mounts to the exhaust.
Inspect the differential pressure sensors located before and after the DPF (bank 2). Look for burned wires or loose/corroded connectors. Separate connectors and check for bent or corroded pins. Ensure sensor wires aren’t resting on the DPF. Start the truck and check for leaks on or around the unit.
If everything checks out in the above steps, drive the truck for about 30 minutes at highway speed to sufficiently increase exhaust temperature for DPF regeneration. Personally, I’ve found idling the engine at 1400 RPM for about 20 minutes achieves the same results.
If the problem persists after highway driving, the best approach is to take it to a shop and connect it to a diagnostic computer like Tech II. This is inexpensive and they can monitor sensors and ECU in real time. They can see sensor signals and whether the ECU is actually attempting the regeneration process. The faulty component is quickly identified.
If you primarily do city driving and this is a recurring issue, there’s another solution. Most shops can reprogram your computer to disable the regeneration process quickly. Then remove the DPF and replace it with a straight pipe (if legal in your jurisdiction). Problem solved. Don’t discard the DPF though – it’s worth significant money if you sell it or need it in the future.
NOTE: Some modifications like cold air intake (CAI) kits or cat-back exhaust kits can trigger this code and may also affect your manufacturer’s warranty. If you have such a modification and get this code, reinstall the stock part and see if it clears the code. Or try contacting the kit manufacturer to see if this is a known issue.