OBD-II Code P0259 — What It Means & How to Fix It

What Does This Error Mean?

P0259 means the injection pump fuel metering control circuit on Bank B has an intermittent fault. The problem is not constant — it comes and goes, which is why the code says 'intermittent'. This makes it harder to diagnose than a steady fault. You might notice occasional rough running, a brief power loss, or a check engine light that keeps coming back. Intermittent faults typically worsen over time — don't wait until it becomes a full breakdown.

Affected Models

All diesel vehicles 1996+
Common in diesel trucks with high mileage
Common in Ford Power Stroke V8 engines
Common in GM Duramax diesel trucks
Common in any diesel with an aging injection system

Common Causes

Loose or intermittently connecting wiring plug at the Bank B injection pump
Hairline crack in the Bank B solenoid wiring that opens under heat or vibration
Aging metering solenoid beginning to fail intermittently before complete failure
Corrosion on connector pins creating variable resistance
Intermittent internal pump fault in the Bank B metering valve

How to Fix It

Document when the light comes on. Note the conditions — cold start, hard acceleration, hot weather, or highway speed. This pattern is valuable information for the technician diagnosing the fault.

Take a photo of the scanner readout each time you check — it helps build a history of when the fault occurs.
Perform the wiggle test: with the engine running, wiggle the wiring harness and connector at the injection pump Bank B connection. If the engine stumbles or the code sets, the connector or wire is your problem.

This simple test catches a large percentage of intermittent electrical faults in minutes.
Clean and re-seat the Bank B pump connector. Corroded or partially unseated connectors are a very common cause of intermittent codes. Apply dielectric grease and ensure the lock tab engages fully.

If the connector shows heavy corrosion, replace it entirely rather than just cleaning it.
Inspect the Bank B wiring harness for sections that are close to hot exhaust components or areas that vibrate. Heat cycling and vibration crack wire insulation over time, creating faults that only appear under certain conditions.

Look for shiny spots or worn areas on the harness outer jacket — those indicate rubbing.
If the fault can't be reproduced during inspection, ask a diesel shop to data-log the vehicle. They can attach a scanner and have you drive normally until the fault appears, then review the recorded data.

Some shops offer loaner data loggers — you drive the car yourself and return the device when the fault occurs.

When to Call a Professional

Intermittent codes are the most difficult to diagnose — a fault that isn't present during a shop inspection cannot be tested. A diesel specialist with a data logging scanner can monitor Bank B live during normal driving to catch the fault in real time. Don't let any shop replace the injection pump based solely on an intermittent code without first confirming the fault.

Frequently Asked Questions

Why does my P0259 code keep coming back after I clear it?

Because the fault is still there — you've only cleared the warning, not fixed the problem. Clearing codes without fixing the underlying issue is like turning off a smoke alarm without looking for the fire. The code will return every time the driving conditions trigger the fault again.

Will P0259 get worse over time?

Almost certainly yes. Intermittent faults are usually caused by something that's gradually degrading — a connector corroding, a wire cracking further, or a component wearing out. What starts as an occasional code usually becomes a permanent code and then a drivability problem. Fix it before you're stranded.

How much does it cost to fix P0259?

If it's just a connector issue: $50–$200. Wiring repair: $100–$400. Bank B solenoid replacement: $200–$700. Injection pump rebuild or replacement: $800–$2,500. Diagnosis at a diesel specialist: $100–$200 — money well spent before buying parts.