P0251 Injection Pump Fuel Metering Control A Malfunction
OBD-II Trouble Code Technical Description
ASE Certified Master Technician
Injection Pump Fuel Metering Control A Malfunction (Cam/Rotor/Injector)
What does that mean?
This generic powertrain/engine diagnostic trouble code can typically apply to all diesel fueled OBD-II equipped engines (e.g. Ford, Chevy, GMC, Ram, etc.), but shows up more often in certain Mercedes Benz and VW vehicles.
Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
The Injection Pump Metering Control Circuit "A" is usually found mounted inside / on the side of the injection pump bolted to the engine. The Injection Pump Metering Control Circuit "A" is usually made up of a Fuel Rack Position (FRP) Sensor and a Fuel Quantity Actuator.
The FRP sensor converts the amount of diesel fuel being delivered by the Fuel Quantity Actuator to the injectors into an electrical signal for the Powertrain Control Module (PCM).
The PCM receives this voltage signal to determine how much fuel it will put into the engine based upon engine operating conditions. This code is set if this input does not match normal engine operating conditions stored in the PCM’s memory, even for a second, as this diagnostic trouble code demonstrates. It also looks at the voltage signal from the FRP sensor to determine if it is correct at initial Key On.
The code P0251 Injection Pump Fuel Metering Control A Malfunction (Cam/Rotor/Injector) could have been set because of mechanical (typically EVAP system mechanical issues) or electrical (FRP sensor circuit) issues. These cannot be overlooked in the troubleshooting stage, especially when dealing with an intermittent problem. Refer to a vehicle specific repair manual to determine which is the "A" part of the circuit for your particular application.
Troubleshooting steps may vary depending upon manufacturer, type of FRP sensor and wire colors.
What is the severity of this DTC?
Severity in this case will be not severe. Since it is electrical failure, the PCM can compensate adequately for it.
What are some of the symptoms of the code?
Symptoms of a P0251 trouble code may include:
- Malfunction Indicator Lamp (MIL) illumination
- Decrease in fuel economy
What are some of the common causes of the code?
Causes for this P0251 code may include:
- Open in the signal circuit to the FRP sensor - possible
- Short to voltage in the signal circuit to the FRP sensor - possible
- Short to ground in the signal circuit to the FRP sensor - possible
- Open in power or ground at FRP sensor - possible
- Failed FRP Sensor - likely
- Failed PCM - unlikely
What are some P0251 troubleshooting steps?
A good starting point is always to check for technical service bulletins (TSB) for your vehicle. Your issue may be a known issue with a known fix put out by the manufacturer and can save you time and money during diagnosis.
Next, locate the FRP sensor on your vehicle. This sensor is usually found usually found mounted inside / on the side of the injection pump bolted to the engine. Once located, visually inspect the connector and wiring. Look for scraping, rubbing, bare wires, burn spots or melted plastic. Pull the connector apart and carefully inspect the terminals (the metal parts) inside the connector. See if they look burned or have a green tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning of the terminals is needed. Let dry and apply electrical grease where the terminals contact.
If you have a scan tool, clear the diagnostic trouble codes from memory, and see if P0251 code returns. If it does not, then the connections were most likely your problem.
If the P0251 code does return, we will need to test the FRP sensor and its associated circuits. With the Key Off, disconnect the electrical connector at the FRP sensor. Connect a Digital Voltmeter black lead to the ground terminal at the FRP sensor wiring harness connector. Connect the red lead of the Digital Voltmeter to the power terminal at the FRP sensor wiring harness connector. Turn Key On Engine Off. Check manufacturer’s specifications; voltmeter should read either 12 volts or 5 volts. If not, repair the power or ground wire, or replace the PCM.
If the prior test passed, we will need to test the signal wire. With the connector still disconnected, move the red lead of the voltmeter from the power wire terminal to the signal wire terminal. The voltmeter should now read 5 volts. If not, repair the signal wire, or replace the PCM.
If all prior tests have passed and you continue to get a P0251, this would most likely indicate a failed FRP sensor / Fuel Quantity Actuator, although a failed PCM could not be ruled out until the FRP sensor / Fuel Quantity Actuator had been replaced. If unsure, seek assistance from a trained automotive diagnostician. PCMs must be programmed, or calibrated to the vehicle to be installed correctly.
Related P0251 DTC Discussions
- 98 chevy diesel code p0251 ?
98 chevy diesel code p0251 inj pump fuel metering what do I repair?the engine stalls at times but will start again I also have code p0231 it seems to stall as the engine begins to warm up but not so much if I keep the rpm,s a little higher 2500 plus...
- 2003 Ram 2500 SLT Cummins 5.9 P0652, P0237, P2269, P0193, P2509, P0341, P0251, P2266
I've recently been having issues with my 2003 Dodge Ram 2500 5.9. Whenever it gets wet or it rains, my truck will start to stall/hiccup and eventually shut off. the check engine light will come on and stay on for about a day or two. When I try to start it after it stalls, it turns over for a while.....
- P0251 Mondeo no start!
2003 TDCI 2.0ltr Mondeo (Delphi system), 154,000mls, removed injectors to recode, refitted, bled out, recoded using Snap-On Verdict, now it will not start.... DTC p0251 came up once and no injectors signal, there is fuel gushing forth at injector pipe unions, live data shows 320BAR rail pressure on ...
- Codes P0251a and P1216 on GMC 6.5L diesel
I am attempting to repair a 1998 GMC G series van with the 6.5L diesel motor that has set the P0251a code. When the codes are cleared this code comes back as soon as the engine is turned over. It is hard to start at times. Does any one have any info as to the source of this code? What component nee...
- 2002 Mondeo Diesel P2338 P1211 P0251 P1102 C1123 C1312
P2338 Cylinder 3... and other errors*Help with coding injectors* Hello, The car have the preheating light intermittent, engine off while driving, lack of power. First I though the injector in cylinder 3 was bad, I cleaned with ultrasonic and coded with autocom delphi in order of cylinders (not fi...
- p0404, p0490, p0190 & p0251 on ford mondeo 2.0 tdci 2003
Hi I am owning a ford mondeo (europe) 2000cc tdci 115ps build in 2003. Engine code is either HJBA or HJBB. 278.000km done. I have had some trouble lately with accelerating, mostly around 3000rpm the engine kicks into emergency running, and after overloading the engine, the engine falls out. But as ...
- 1996 Chevy Truck 2500 P0251 and P0370
I have a 1996 Chevy Truck with a 6.5 Diesel engine. It is very hard to start. It has 2 codes P0251 and P0370. Any ideas?...
- 2000 GMC 6.5l Diesel 4x4 trouble code P0272 and P0380 P1216 P0238 P0251
Ok so it says Cylinder 4 Contribution/Balance. What could cause the problem? It has started making a loud noise that sounds like it is coming from the air intake area. I had originally though it was a burn valve but now I am thinking it may be a faulty injector. Any ideas? There are a few other...
Need more help with a P0251 code?
If you still need help regarding the P0251 trouble code, please post your question in our FREE car repair forums.
NOTE: This information is presented for information purposes only. It is not intended as repair advice and we are not responsible for any actions you take on any vehicle. All information on this site is copyright protected.