Skip the auto shop - Our mechanics make house calls

Q: Fuel rail pressure is all over the place and the truck bucks badley going down the road. Only code that comes up is P215a.

asked by on

Fuel rail pressure is all over the place and the truck bucks badley going down the road. Only code that comes up is P215a. The speed sensor on rear differential was just replaced. This all started happening right after I blew the serpentine belt and replaced my powersteering pump

My car has 140000 miles.
My car has an automatic transmission.

The fuel pressure will fluctuate when the motor is bucking. The trick is knowing if the engine is bucking because of fuel pressure, or is the fuel pressure erratic because of the engine bucking. Usually it has nothing to do with fuel pressure. The fuel rail pressure on a diesel is created by the injection pump, which on a diesel engine changes speeds with engine RPM. So I would expect to see fuel rail fluctuation like this.

Your code indicates there is a possible problem with the CAN (computer area network) that monitors and controls the ABS system. The ABS, the TCM (transmission control module) and the PCM (powertrain control module) all talk with each other over this network. To diagnose this system you will need a scanner to monitor the data from these computers. A scanner isn’t the same as a code reader.

It isn’t a common problem for this system to cause drivability issues, but since this code brings into question the CAN system, which can affect every module on the truck, it is something that should be considered. The most common failure for this vehicle is a fuel injector. With the scanner connected, you need to look at the misfire counters for each cylinder. If one is showing misfires but the others are not, you can suspect that injector is faulty.

Injectors are expensive, so I wouldn’t go out an buy one without some additional diagnosis, but this should get you started. If you still need assistance, a certified mobile mechanic from YourMechanic can visit your home or office to inspect your truck’s bucking issues.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Fuel rail pressure is all over the place and the truck bucks badley going down the road. Only code that comes up is P215a.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Fluid leak between engine and transmission possible slave cylinder

First check the fluid level in the clutch master cylinder to see if it is getting low. If it is low on fluid then you have a slave cylinder leaking. If the fluid does not go low then you do...

Q: AC only working at lowest speed

Hello! We will be happy to help. If the AC is blowing cold on one speed but does not on others it leads me to believe that that AC system itself is working properly. Therefore, I would look more towards...

Q: How long and what is the process to replace a fuel pressure sensor?

A professional mechanic would require roughly 5 hours. (If just the regulator is replaced that takes about 1 hour). Some parts, as noted below, cannot be re-used, you need a precision inch pound torque wrench, FSM instructions (and TSB updates...

Related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.