P2674 — Injection Pump Fuel Calibration Not Learned #

Note: The description for this code may vary depending on the vehicle manufacturer.

• Fuel Metering Calibration Not Learned (General Motors)
• Fuel Injection Pump Calibration Incomplete (Ford)
• Injection Pump Learning Not Performed (Dodge/RAM)

Summary of DTC P2674 #

P2674 is a diagnostic trouble code (DTC) that indicates the vehicle’s engine control module (ECM)—sometimes called the powertrain control module (PCM)—has detected that the injection pump fuel calibration procedure was not completed or successfully learned. The injection pump is responsible for delivering precise amounts of fuel to the engine’s injectors under very high pressure. Proper calibration is critical to ensure optimal engine performance, emissions, and fuel economy. This code often appears after pump replacement, ECM reprogramming, or certain types of fuel system repairs, signaling that calibration is incomplete. Ignoring this code can lead to drivability issues or even long-term engine damage.

Common Symptoms for DTC P2674 #

When P2674 is stored, you might notice a variety of symptoms—some subtle, others more pronounced. Since the injection pump isn’t calibrated, the engine may not receive the optimal amount of fuel, leading to performance problems. Typical symptoms can include:

• Rough idle or unstable engine RPMs
• Hard starting or extended cranking times
• Reduced power output or poor acceleration
• Increased exhaust smoke (black or white)
• Illuminated check engine light
• Decreased fuel efficiency

Probable Causes for Code P2674 #

The causes behind P2674 typically relate to recent service events or faults in the fuel system’s calibration process. Some are more common than others. Here’s what may be triggering this code, in order of likelihood:

1. Injection pump replaced without performing the required calibration procedure.
2. ECM/PCM reprogramming or replacement without recalibrating the fuel system.
3. Incomplete or failed fuel calibration procedure due to technician error or interrupted process.
4. Wiring or connector issues between the injection pump and ECM/PCM.
5. Software or firmware issue in the ECM/PCM preventing the calibration data from being stored.
6. Faulty injection pump not responding correctly to calibration commands.

Step-by-Step Diagnostic for P2674 #

Diagnosing P2674 requires a structured approach so you don’t chase your tail. Always start with the basics before diving into advanced troubleshooting. Follow these steps:

• 1. Confirm the code with a reliable OBD-II scanner and record freeze frame data.
• 2. Verify recent service history: Ask if the injection pump, ECM/PCM, or related components have been replaced or serviced.
• 3. Inspect wiring and connectors between the injection pump and ECM/PCM for corrosion, loose pins, or damage.
• 4. Attempt the OEM-specified calibration procedure using an appropriate scan tool. Follow the service manual instructions to the letter.
• 5. Check for software updates for the ECM/PCM that may address calibration retention issues.
• 6. If calibration fails: Re-examine all connections, double-check compatibility of parts, and ensure correct equipment is used.
• 7. Clear codes and test drive to see if P2674 returns after a successful calibration.

Possible Repairs for P2674 #

The remedy for P2674 depends on the root cause. Most often, it’s a procedural oversight rather than a major component failure. Here’s what you might need to do:

• Perform the injection pump calibration procedure using a factory scan tool or its equivalent.
• Update or reprogram the ECM/PCM with the latest OEM software.
• Repair or replace damaged wiring or connectors between the ECM/PCM and injection pump.
• Replace the injection pump if it’s found to be unresponsive to calibration commands (rare).
• Repeat calibration if the last attempt was interrupted or not completed properly.

Is It Safe to Drive with Code P2674? #

Limited. While the vehicle may still be operable, driving with P2674 is not recommended for extended periods. An uncalibrated injection pump can result in poor performance, higher emissions, and potential engine damage over time. If you notice severe symptoms like hard starting or excessive smoke, minimize use and have the issue addressed as soon as possible to avoid secondary damage.

Vehicles Most Commonly Affected by P2674 #

P2674 is seen most frequently on modern diesel engines where precise fuel delivery is critical. Some vehicle families are more likely to store this code, especially after service or component replacement. Commonly affected include:

• GM Duramax diesels (Chevrolet Silverado, GMC Sierra)
• Ford Power Stroke diesels (F-Series Super Duty, Transit)
• Dodge/RAM Cummins diesels (RAM 2500/3500)
• Some European diesels (Opel, Vauxhall, Peugeot) using Bosch or Denso systems

Common Mistakes & Best Practices for P2674 #

It’s not uncommon for this code to reappear if the calibration procedure isn’t done exactly as the OEM prescribes. Here’s what to watch out for:

• Skipping the calibration step after pump or ECM/PCM replacement.
• Using an incompatible scan tool that can’t perform the full calibration process.
• Ignoring wiring/connectivity checks when calibration fails.
• Failing to check for software updates which may resolve calibration retention issues.
• Not documenting service history, leading to repeated mistakes.

Quick FAQ: P2674 #

Here are a couple of common questions and succinct answers:

• Q: Can I clear P2674 with a basic OBD-II scanner?
  A: You can clear the code, but it will likely return unless the calibration procedure is completed with a capable scan tool.
• Q: Do I need to replace the pump if I see P2674?
  A: Not usually. Most P2674 cases are resolved by performing the correct calibration. Only replace the pump if it fails to respond to calibration commands after all other checks.