P0259: Injection Pump Fuel Metering Control B High (Meaning, Causes, Fixes)
What P0259 means
On diesel engines with an injection pump, the fuel metering control 'B' sits on or inside the pump. OBD-Codes.com describes it as a fuel rack position (FRP) sensor plus a fuel quantity actuator: the sensor turns the amount of fuel the actuator is delivering into a voltage signal, and the powertrain control module (PCM) uses it to decide how much fuel to give the engine. OBD-Codes.com says P0259 sets when the voltage at the sensor stays above a set level (usually over 4.8 V) for too long, and that it is usually an electrical circuit issue. RepairPal explains it in terms of pump pressure: the fuel pump control actuator controls the injection pump's output pressure, and the PCM sets P0259 when it detects an incorrect signal from that actuator. OBD-Codes.com says the code applies to diesel OBD-II engines generally but shows up more often on some Mercedes-Benz and VW vehicles. It is the 'B' counterpart of P0254, and which part of the circuit counts as 'B' depends on the vehicle, so check its service information.
Severity: can I keep driving?
Drive with caution, fix soon
Get it checked soon. The sources disagree here: OBD-Codes.com says P0259 is not severe because it is an electrical fault the engine computer can compensate for, while RepairPal rates it 'Urgent' and says the engine may lose performance or stall. Since a stall can happen while driving, don't put off a diagnosis.
Common symptoms
- Check engine light on (OBD-Codes.com)
- Decrease in fuel economy (OBD-Codes.com)
- Decreased engine performance (RepairPal)
- Engine may stall (RepairPal)
Likely causes
Roughly most to least common, based on the sources below. Your vehicle may differ.
- Open in the power or ground circuit at the fuel rack position sensor, rated likely by OBD-Codes.com
- Short to power in the signal circuit to the fuel rack position sensor (OBD-Codes.com)
- Failed fuel rack position sensor / fuel injection pump actuator (both sources)
- Wiring issue (RepairPal)
- Fuel injection pump failure (RepairPal)
- Failed PCM, rated unlikely by OBD-Codes.com (both sources)
Diagnostic steps you can do
Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.
- Check for technical service bulletins for your year, make and model first, since the issue may be known with a known fix.
- Find the sensor connector on or beside the injection pump and look over the wiring and connector for rubbing, bare wires, burn marks or melted plastic.
- Unplug the connector and check the terminals for burning or green corrosion. OBD-Codes.com suggests cleaning them with electrical contact cleaner and a plastic brush, letting them dry and applying electrical grease.
- Clear the code with a scan tool and drive. If it doesn't come back, OBD-Codes.com says the connection was most likely the problem.
- If the engine stalls or loses power, have it diagnosed promptly rather than continuing to drive it.
Typical fixes
- Clean or repair corroded or damaged connectors at the pump sensor
- Repair shorted or open signal or power wiring
- Replace the fuel rack position sensor / fuel quantity actuator if circuits test good
- Replace the fuel injection pump if it is at fault (RepairPal lists fuel pump replacement as the common repair)
- Replace and program the PCM only after the other parts are ruled out
Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.
🛠 When to call a pro
- OBD-Codes.com's test: key off, unplug the sensor, then key on engine off and measure between the harness power and ground terminals; expect 12 V or 5 V depending on the manufacturer's spec, otherwise repair power or ground or suspect the PCM. Then measure the signal terminal to ground, which should read 5 V; if not, repair the signal wire or suspect the PCM.
- If all circuit tests pass and the code keeps returning, OBD-Codes.com points to the FRP sensor / fuel quantity actuator, and says the PCM can't be ruled out until that part is replaced. A replacement PCM must be programmed to the vehicle.
- The sources disagree on severity and focus: OBD-Codes.com calls it not severe and treats it as an electrical circuit fault, while RepairPal rates it 'Urgent', lists stalling, and names the injection pump itself and fuel pump replacement as common repairs.
Where to buy
Plain search links. Always match parts to your exact year, make, model and engine.
FAQs
Can I drive with P0259?
Possibly for a short time, since OBD-Codes.com says it's an electrical fault the PCM can usually compensate for. But RepairPal rates the code 'Urgent' and says the engine may stall, so get it diagnosed soon and avoid long trips until it is.
What usually causes P0259?
OBD-Codes.com points to wiring first: an open in the sensor's power or ground (likely) or a short to power in its signal circuit, with a failed sensor possible and a failed PCM unlikely. RepairPal lists the injection pump actuator, the pump itself, wiring and the PCM.
What's the difference between P0259 and P0258?
Both are for the injection pump fuel metering control 'B'. P0258 means its signal stayed too low, and P0259 means it stayed too high (OBD-Codes.com says usually over 4.8 V).
Does P0259 always mean a new injection pump?
No. OBD-Codes.com recommends checking service bulletins, connectors and wiring first, then testing the sensor circuit. Corroded or damaged connections can set it, and clearing the code after fixing them may be all that's needed.
Sources
Last reviewed 2026-10-26. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.