Technical Description of OBD-II Trouble Code
Error in Fuel Timing
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code, which means it applies to OBD-II equipped vehicles (Dodge, Ram, Ford, GMC, Chevrolet, VW, Audi, etc.). Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
If your OBD II equipped vehicle displays a code P0149, it indicates that the powertrain control module (PCM) has detected a malfunction in the timing sequence of the fuel pump. I have never encountered this code in a vehicle that does not have a diesel engine.
Most of today’s clean burning, direct injection diesel engines use a mechanical fuel pump that is driven directly off the crankshaft. To overcome the high compression ratios associated with diesel engines, this type of pump is timed in sequence with the position of the crankshaft to provide a high-pressure injection pulse (up to 44,000 psi) at a precise point and interval for each cylinder of the engine. The fuel pump is usually small enough to fit underneath the intake manifold and integrates the low-pressure pump, high-pressure pump, fuel timing solenoid, and fuel pressure control actuator. There is also likely to be a fuel pressure sensor nearby.
The fuel pump is pulsed using a toothed sprocket that aligns with a toothed sprocket on the front of the crankshaft. The timing of these two sprockets (using a steel chain) is crucial for fuel pump timing and fuel delivery. If the two sprockets are misaligned by even a single tooth, a code P0149 may be stored.
The PCM uses inputs related to engine RPM and engine load to calculate fuel timing advance. The electronic fuel timing solenoid, controlled by the PCM, allows direct injection timing to be advanced according to engine speed and load.
The electronic fuel pressure regulator, also controlled by the PCM, is responsible for controlling fuel pump pressure. The fuel pressure sensor monitors fuel pressure while the engine is running and provides the PCM with an actual reading so that it can continue to plot fuel pump timing and monitor fuel pressure requirements. If the PCM detects a fuel pressure input signal indicating a problem with fuel pump timing, a code P0149 will be stored and a malfunction indicator lamp may illuminate.
NOTE: Please exercise extreme caution when attempting to service the high-pressure fuel system. This type of system should only be serviced by trained personnel. Consult a reliable vehicle information source (such as All Data DIY) for more precautions.
Code Severity & Symptoms
If the vehicle starts, inconsistencies in fuel pump timing can result in engine damage. A stored code P0149 should be considered severe.
Symptoms of a P0149 code may include:
Causes
Possible causes for this code to be set are:
Diagnostic and Repair Procedures
A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known problem with a known solution provided by the manufacturer, which can save you time and money during diagnosis.
Although a stored code P0149 may be caused by either a mechanical failure or an electrical issue, mechanical failure is unlikely unless recent related repairs have been performed. If the engine and/or the high-pressure fuel pump have recently been re-timed, suspect a misalignment of the corresponding timing marks that has caused this code to be stored.
Unless there is a mechanical glitch, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a vehicle information source like All Data DIY to diagnose a code P0149.
Connect the scanner to the vehicle diagnostic connector to retrieve all stored codes and freeze frame data. Write down this information in case you need it later, then clear the codes and proceed.
If there is a strong fuel odor, suspect a fuel leak as the root cause of your problem. If a fuel leak is detected, carefully inspect fuel system components that have been recently replaced. Once you have visually inspected all fuel delivery lines and components, repair any leaks as necessary and retest the system to see if the code is reset.
Use the DVOM to test the fuel pressure sensor, fuel control actuator, and fuel timing solenoid as recommended in your vehicle information source. Replace components that fail to meet the manufacturer’s recommended specifications and retest the system.
If you continue to experience issues, use your vehicle information source to search for technical service bulletins (TSB) that match your specific vehicle, symptoms, and code/s. The information contained therein may help you pinpoint the malfunction and rectify the situation.
Additional diagnostic notes:
