OBD-II Code P0258 — What It Means & How to Fix It

What Does This Error Mean?

P0258 means the injection pump fuel metering control signal on Bank B is reading too high. The engine computer is seeing an over-voltage or over-signal condition on the Bank B metering circuit. This diesel-specific code can cause one bank of cylinders to receive too much fuel. Expect symptoms like black smoke, rough idle, over-rich exhaust, and excess fuel consumption. Address it promptly — long-term over-fueling damages injectors and clogs emissions components.

Affected Models

All diesel vehicles 1996+
Common in Ford Power Stroke V8
Common in GM Duramax V8 diesel
Common in heavy-duty diesel pickups and vans
Common in European diesel vehicles with Bosch systems

Common Causes

Short to voltage in the Bank B metering solenoid wiring
Internally shorted Bank B metering solenoid stuck delivering excess fuel
Shorted or bridged connector pins at the Bank B pump connection
ECM sending an over-voltage command signal to Bank B
Injection pump internal valve failure causing uncontrolled fuel delivery on Bank B

How to Fix It

Scan for all trouble codes. A short-to-voltage fault often generates companion codes in the same circuit. Seeing additional electrical codes helps identify whether this is a wiring problem.

Clear the codes after noting them, drive the vehicle, and see which codes return first.
Inspect the Bank B wiring harness for any section that may have rubbed through its insulation and made contact with a power wire or battery positive circuit. This is the most common cause of high-signal codes.

Check carefully near the battery, the firewall, and anywhere the harness is routed near exhaust or sharp metal edges.
Measure the voltage at the Bank B metering solenoid connector with the key on, engine off. If voltage is significantly above the 5V reference signal spec, you have a confirmed short to power.

Reference your vehicle's service manual for the exact expected voltage — specs vary by manufacturer.
Inspect the pump connector for shorted pins. Even a tiny metal fragment or water intrusion inside the connector can bridge the reference signal wire to a power wire.

Replace the connector if there's any visible corrosion damage or pin spreading.
If wiring tests are clean, have the injection pump professionally tested. A stuck-open metering valve on Bank B delivers too much fuel regardless of the ECM command — and will need rebuild or replacement.

Ask the diesel shop to check whether the solenoid assembly alone can be replaced.

When to Call a Professional

High-signal injection faults require proper diagnostic equipment to confirm the source of the excess voltage. A diesel specialist can use a live data scanner to monitor actual vs. commanded fuel delivery per bank. Don't replace the injection pump without first confirming the pump is actually at fault. Shops that specialize in diesel injection systems are the right choice here.

Frequently Asked Questions

What does over-fueling actually do to an engine?

Too much fuel means some of it doesn't burn completely. Unburned fuel washes oil off cylinder walls, causing premature wear. It also clogs the diesel particulate filter (DPF) and damages the catalytic converter. You'll notice black smoke from the exhaust and a fuel smell. Long-term, it shortens engine life significantly.

Could the ECM be sending a bad signal and cause P0258?

Yes, though it's not the most common cause. If the ECM's Bank B output driver circuit has failed, it may send too much voltage to the solenoid. But wiring shorts are far more common than ECM failures. Always rule out the wiring before suspecting the ECM — testing the ECM typically requires the help of a specialist.

How much does it cost to fix P0258?

Wiring repair: $100–$400. Connector replacement: $50–$200. Bank B solenoid: $200–$700. Full injection pump: $1,000–$2,500 installed. ECM replacement (if needed): $500–$1,500 depending on vehicle.