OBD-II trouble code
P0256: Injection Pump Fuel Metering Control "B" (Cam/Rotor/Injector)
SAE J2012 APR2002: metering control B. The Chrysler PWM reprints are titled P0251 and describe one actuator. The printed pair is diagnosis only.
Quick facts
- System
- Powertrain
- Category
- Fuel & Air
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $125 – $183 (check engine light diagnosis and testing, labor only; the diesel injection pump averages are outside this pair)
- DIY difficulty
- Advanced DIY
Browse every code in P0200–P0299, or start from the full code library.
What does P0256 mean?
SAE J2012 APR2002 names P0256 Injection Pump Fuel Metering Control "B" (Cam/Rotor/Injector). Section 3.8 says the letter is manufacturer-defined, starting with A. P0251 is channel A. Nothing in the name says B is a second pump, a rear pump, or the harder one to reach. The diagram either shows a second metering control or it does not.
The public Chrysler reprints found for this pass are headed P0251, CP3 pump regulator control, and they describe one electronic fuel control actuator. Their lamp, their less-than-10-ohm lines, and their greater-than-1-volt lines are that chart. They were not found with a B label, and the circuit numbers already disagree inside the A chart (K604/K65 versus K181/K31). Copying either pair onto P0256 adds a second error. NHTSA MC-10212505, the 2019–2020 Ram 6.7 metal-contamination bulletin, lists P0087, P008A, and P0201 through P0206. It does not list P0256, and it does not describe a B actuator.
RepairPal's national diesel pump average of $2,630–$4,034 and the Ram 3500 line of $3,384–$7,376 were searched. Neither listing says channel B. Diagnosis labor is the printed pair. Do not open a high-pressure fitting because this code is stored. Depressurize before a low-pressure connection is opened.
Common causes
- An open wire in metering-control B
- A short in that control circuit, when the calibrator files it on this general row
- Metering control B not responding to its command
- A connector or terminal on control B
Symptoms
- P0256 stored
- One metering actuator on the diagram, which has to be reconciled with a B code before parts are ordered
- No B pin list from the documents that were read
- P0251 stored on the A actuator, a separate code
Diagnostic steps
- 1.Read the diagram for a second metering control and for the letter the calibrator stored. Do not assign B to the actuator the P0251 chart already uses.
- 2.Do not connect the 20-second test lamp, and do not apply the 10-ohm or 1-volt sentences, until the VIN procedure is a P0256 procedure. The copies found are P0251.
- 3.If the diagram shows one actuator, stop and confirm the code number. Testing A's connector under B's name will not clear a misread.
- 4.Leave MC-10212505 on its own DTC list. Do not open the high-pressure side. Depressurize a low-pressure fitting before it is opened.
- 5.The printed pair is diagnosis labor. Both pump prices were searched and left outside.
- 6.Verify against P0256 specifically, key on, in the bay.
Repair cost
$125 – $183 (check engine light diagnosis and testing, labor only; the diesel injection pump averages are outside this pair)
RepairPal's check engine light diagnosis and testing, updated 3 September 2026, is $125–$183 labor. The printed pair is that figure. Diesel injection pump replacement is $2,630–$4,034 nationally. The Ram 3500 estimator is $3,384–$7,376 and lists other year lines, including $1,034–$1,182 and $3,288–$10,622. A fuel filter is $258–$322. All were searched. None is identified as metering control B.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with check engine light diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.