P0253 code definition
This trouble code identifies an Injection Pump Fuel Metering Control “A” Low (Cam/Rotor/Injector) problem.
What the P0253 code means
This code only ever gets stored on the PCMs (Powertrain Control Module) of diesel engines. It means that the vehicle’s PCM has detected an inconsistency between the electronic fuel control actuator’s signal voltage that was sent out and the one returned by the fuel metering sensor control.
All diesel injection systems rely on some type of an electronic fuel control actuator which is responsible for measuring the amount of fuel that is allowed into the actual pumping chamber of a high pressure diesel fuel pump. Therefore, this device determines how much fuel is going to be delivered to the fuel rail and by how much pressure.
This pressure needs to be controlled, though, and the acceptable range is very narrow. The vehicle’s PCM is constantly checking in on this process through a variable resistance sensor. If the vehicle’s PCM notes that the reading is inaccurate due to an inconsistency between signals, this code gets stored.
What causes the P0253 code?
There are a few common reasons behind the P0253 code getting stored:
The fuel filter has become clogged or dirty
The fuel pump is defective
The fuel control actuator driver inside the PCM is actually faulty
This last possibility is pretty rare.
What are the symptoms of the P0253 code?
Sometimes, there will be only minor symptoms associated with this problem. The Check Engine Light may come on, for example, but nothing more. Other times, though, more noticeable symptoms may appear, such as:
- The engine has trouble starting
- The engine won’t start at all
- The exhaust produces excessive smoke
- The engine misfires
- The engine struggles to accelerate
How does a mechanic diagnose the P0253 code?
A mechanic will need to do the following to diagnose the problems associated with the P0253 code:
- Use an OBD-II scanner to download the vehicle’s stored codes.
- They’ll examine the circuitry and connectors between PCM and fuel control actuator.
- Next, they’ll look at the circuitry and connectors
- If any of the more serious symptoms were reported by the customer, the mechanic will try to recreate them.
Common mistakes when diagnosing the P0253 code
Far too often, a mechanic sees this code and immediately goes to work replacing the injector pump or injectors. However, more often than not, it’s the fuel filter that is the problem. After that, the most common problem is usually the wiring and/or connectors.
How serious is the P0253 code?
The most serious concern attached to the P0253 code – or any trouble code reported from a diesel-engine vehicle – is that an amateur will try fixing the problem on their own. These engines work under extremely high pressures and can be extremely dangerous, especially if the amateur is trying to work on a fuel pump.
Outside of that, this is still a problem that should get fixed right away before it turns into something worse. Anytime the engine is struggling, there’s a risk that a bigger problem is brewing.
What repairs can fix the P0253 code?
Otherwise, the mechanic probably doesn’t have to do much more than examine the connectors and circuits coming from the fuel control actuator and connecting to the PCM. Chances are they’re frayed, damaged or shorted and just need to be repaired or replaced.
Additional comments for consideration regarding the P0253 code
When working on a diesel engine’s fuel system, it’s essential that the mechanic observe safety guidelines, especially if they intend to release any of its residual pressure before proceeding with repairs.
Need help with a P0253 code?
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