P0259 Code - Injection Pump Fuel Metering Control 'B' Low
Quick Answer
This fault code is stored in the Engine Control Module (ECM) when the system cannot correctly control the fuel pressure. Common causes include Faulty Fuel Pump, Fuel Pump harness is open or shorted, Fuel Pump circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0259 indicates Injection Pump Fuel Metering Control 'B' Low.
- Common causes
- Common causes include Faulty Fuel Pump, Fuel Pump harness is open or shorted, Fuel Pump circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0259 Description
Normally manufacturers will support data parameters for actual and desired fuel pressure.
A number of issues may cause this fault code to be set such as a faulty fuel rail pressure sensor, a mechanical fault with a fuel inlet metering valve could cause the valve to become stuck. An electrical fault such as an open circuit in the fuel inlet metering valve on a system with a normally closed valve will also cause this situation. A short circuit on the control wire of a normally open fuel pressure regulator will also cause this fault.
A fault in the fuel injector return system will cause the fuel pressure to be lower than expected. This causes fuel from the high-pressure circuit to be leaked back to the low-pressure circuit. A faulty maximum pressure relief valve will also cause this situation.
The high-pressure pump should also be tested to ensure it is capable of delivering the required volume of fuel.
What are the Possible Causes of the DTC P0259?
- Faulty Fuel Pump
- Fuel Pump harness is open or shorted
- Fuel Pump circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0259?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0259 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Information for Specific Makes
- P0259 Mercedes-Benz — Injection Pump Fuel Metering Control 'B' Low
Frequently Asked Questions about P0259 Code
1. What does the OBDII code P0259 mean?
P0259 indicates an issue with the Injection Pump Fuel Metering Control 'B' circuit, specifically a low signal detected by the engine control module (ECM).
2. What are the common symptoms of a P0259 code?
Symptoms may include reduced engine power, poor fuel efficiency, rough idling, difficulty starting the engine, or the engine stalling.
3. What causes the P0259 code to appear?
Common causes include a faulty injection pump, damaged or corroded wiring or connectors in the fuel metering control circuit, a clogged fuel filter, or a malfunctioning fuel pressure sensor.
4. Can I drive my vehicle with a P0259 code?
Driving with a P0259 code is not recommended as it can lead to poor engine performance, potential stalling, and increased wear on fuel system components.
5. How is a P0259 code diagnosed?
A technician will typically inspect the fuel system, check the wiring and connectors for damage, test the fuel pressure sensor, and use a scan tool to monitor live data.
6. What repairs can fix the P0259 code?
Repairs may involve replacing the injection pump, repairing or replacing damaged wiring or connectors, cleaning or replacing the fuel filter, or replacing a faulty fuel pressure sensor.
7. Can a dirty fuel filter cause a P0259 code?
Yes, a clogged or dirty fuel filter can restrict fuel flow, causing the ECM to detect low fuel metering control and trigger the P0259 code.
8. How much does it typically cost to fix a P0259 code?
Repair costs can vary widely depending on the root cause, ranging from $100 for a fuel filter replacement to over $1,000 for injection pump replacement.
9. What tools are needed to troubleshoot the P0259 code?
Tools typically include an OBDII scanner, a multimeter for testing electrical connections, and possibly a fuel pressure gauge to check the fuel system.
10. Can a weak fuel pump trigger the P0259 code?
Yes, a weak or failing fuel pump can result in insufficient fuel pressure, which may cause the P0259 code to appear.
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