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DTC codes / P26xx · Computer and output circuits / P2674

P2674Injection Pump Fuel Calibration Not Learned

P2674 indicates that the engine control module (ECM) has not successfully completed the fuel calibration learning process for the injection pump. This means the ECM cannot confirm the precise fuel delivery characteristics of the pump, which is essential for optimal combustion control and emissions compliance.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaComputer and output circuits

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) on the dashboard.
  • Often no symptoms besides the warning light, especially if the vehicle continues to run normally.
  • Reduced engine power or limp mode in some cases, as the ECM may limit performance to protect the engine.
  • Rough idle or hesitation during acceleration if the calibration is significantly off.
  • Increased fuel consumption or poor fuel economy noticed over time.
  • Difficulty starting the engine, particularly in cold conditions, due to incorrect fuel delivery.

Common causes, most likely first

  1. Interrupted or incomplete calibration learning procedure, often due to a battery disconnect or ECM reset without a proper relearn drive cycle.
  2. Faulty fuel pressure sensor or fuel temperature sensor providing inaccurate data to the ECM, preventing successful learning.
  3. Wiring issues such as damaged harness, corroded connectors, or poor grounds in the injection pump circuit.
  4. Sticking or malfunctioning fuel metering valve or solenoid on the injection pump.
  5. Internal mechanical wear or damage within the injection pump affecting its calibration.
  6. Software glitch or outdated ECM calibration that requires a reprogramming update.
  7. Low fuel level or fuel system air intrusion that disrupts the learning process.

How to diagnose and fix it

  1. Verify battery voltage and ensure a stable power supply; clear the code and perform a proper calibration relearn drive cycle as specified by the manufacturer.
  2. Inspect the fuel system for leaks, air intrusion, and proper fuel level; repair any issues and retry the learning procedure.
  3. Check all wiring and connectors related to the injection pump, fuel pressure sensor, and fuel temperature sensor for damage or corrosion; clean and secure as needed.
  4. Test the fuel pressure and fuel temperature sensors with a scan tool to confirm they are reading accurately; replace if out of specification.
  5. Use a bidirectional scan tool to command the fuel metering valve and observe its operation; if unresponsive or erratic, diagnose further.
  6. If all electrical and sensor checks pass, suspect internal injection pump wear; consult a qualified diesel specialist for pump testing or replacement.
  7. After repairs, perform the manufacturer's calibration relearn procedure and verify the code does not return.

Calibration Relearn Is Not Always the Fix

  • A common mistake is assuming the code will clear after a simple battery disconnect; the ECM must complete a specific drive cycle to learn the pump calibration, which often requires a scan tool to initiate.
  • Even minor air bubbles in the fuel system can prevent successful calibration learning, so always check for loose fuel lines or a clogged fuel filter before condemning the pump.
  • The fuel pressure sensor on the rail is a frequent culprit; it may read within range but still have a slow response that disrupts the learning process, so live data analysis is crucial.
  • Some vehicles require a software update to the ECM to correct a calibration learning issue, so check for technical service bulletins before replacing hardware.
  • This code can be set by a weak battery or poor ground connection that causes voltage drops during the learning procedure, so always verify power and ground integrity first.

Can I keep driving with P2674?

The vehicle may be safe to drive short distances to a repair shop, but avoid heavy loads or high-speed driving because the ECM may be operating with default fuel delivery values. Prolonged driving with this code can lead to increased emissions, poor fuel economy, and potential damage to the injection pump or catalytic converter.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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