The light went out on its own. Is the problem gone?

No — it means the fault stopped being present, which is not the same thing. Most modules turn the light off after a set number of drive cycles without the fault recurring, but the code stays in memory as a history code precisely so that the information is not lost. Intermittents on this circuit rarely improve; connectors corrode further, cracked insulation opens wider, and marginal terminals lose more tension. The gap between episodes tends to shorten over time until the fault becomes permanent. The unlit dashboard is a pause, not a repair, and the stored history code is still worth investigating.

Why not just replace the metering actuator to be safe?

Because on an intermittent you will never know whether it worked. If the fault occurs once a week and you fit a new actuator, a week of normal running feels like confirmation — and it is not, because the fault simply has not come back yet. Meanwhile the most likely causes on this circuit are not the actuator at all; they are the connector, the harness, and the ground, all of which are far cheaper to address and all of which produce intermittent behaviour far more readily than a solid-state component does. Hold out for evidence: a captured event in a data log, a visible defect, or a measurement taken while the fault was actually happening.

How do I make the fault happen so I can measure it?

Use the freeze frame to tell you the conditions, then recreate them. If the fault set at high coolant temperature, get the engine fully hot before testing, because a cold workshop test reproduces almost nothing about a thermal fault. If it set under load, drive it under load with a data log running rather than testing in the bay. If it correlates with rough roads, the target is vibration, so a systematic wiggle test of each harness section while watching live data is the right approach. The general principle is that the fault has conditions attached to it, the freeze frame records what they were, and reproducing them is more productive than any amount of testing under conditions where the circuit behaves.

Can I keep driving while I work out what is wrong?

It is not advisable, and an intermittent is arguably worse than a permanent fault in this respect rather than better. A vehicle that runs badly all the time at least tells you something is wrong. A vehicle that runs perfectly and then abruptly loses fuelling gives no warning at all, and on this circuit the failure mode is a fuelling cut or a stall. A diesel stalling while moving takes power steering assist and vacuum brake assist with it. If the intermittent has ever produced a stall while the vehicle was in motion, treat it as unsafe to drive until the fault is found rather than betting on the odds of it not happening again.

OBD-II trouble code

P0255: Injection Pump Fuel Metering Control "A" Intermittent (Cam/Rotor/Injector)

The metering control fault is real, but it will not sit still long enough to be measured. That changes the job completely: on an intermittent, the productive work is capturing the fault, not testing components that are behaving perfectly while you look at them.

High severityPowertrainFuel & AirDo not drive

Quick facts

System: Powertrain
Category: Fuel & Air
Severity: High severity
Drivable: No — stop driving until repaired
Repair cost range: $0 – $1,400
DIY difficulty: Advanced DIY

What does P0255 mean?

P0255 closes the injection pump metering control "A" family, and it is the odd member. P0251 through P0254 describe a fault the module can see when it looks. P0255 describes one that appears, sets a code, and then vanishes — the module caught the metering control misbehaving, stored it, and by the time the vehicle reached a scan tool everything read normally again. The fault is not imaginary. It is just not present on demand.

That single characteristic changes the entire approach, and it is worth stating plainly because it runs against instinct: on an intermittent code, testing components is mostly wasted effort. A meter placed on a circuit that is working correctly at that moment tells you nothing except that the circuit is working correctly at that moment. The productive work is different in kind. It is about capturing the fault — recreating the conditions under which it occurs, and having the data recording when it does.

Start with the freeze frame, which on this code is worth more than on almost any other. It is a snapshot of the exact operating conditions at the moment the fault set: engine speed, load, coolant temperature, vehicle speed, fuel pressure. Read it carefully and look for a pattern. A fault that only sets at high coolant temperature points at heat — expanding metal opening a marginal connection, or insulation that has hardened and cracks apart as it warms. A fault that sets only at low temperature points at fuel gelling or at a connection that shrinks when cold. A fault that sets under load and never at idle points at supply volume or at harness movement caused by engine torque roll. A fault that sets on rough roads points at vibration and terminal tension. Each of those patterns leads somewhere different, and the freeze frame is free.

The physical inspection that follows should target connections rather than components. The metering actuator's connector sits on the injection pump — low on the engine, hot, and vibrating continuously — which makes it the most likely home for an intermittent on this circuit. Check terminal tension against a matching pin rather than by eye, because a terminal that has lost its grip still looks perfectly normal sitting in the housing. Look for green or white deposits on the terminal faces, a hardened or displaced seal, and any sign of water having been in the housing. Then follow the harness looking for the two damage patterns that produce intermittents: shiny, flattened rub spots where it has moved against a bracket or the pump body, and stiff, dark, brittle sections where heat has hardened the insulation to the point where flexing opens a crack.

When you do test, test under the conditions that produce the fault. A wiggle test on a cold engine in a workshop reproduces very little. The same test done at full operating temperature, with a meter or scan tool recording, while you move each section of the pump harness in turn, is one of the highest-yield things you can do on this code. Better still, data-log commanded and actual fuel quantity through a drive that historically triggers the fault, then look at what the other parameters were doing in the moment it dropped out.

One piece of advice deserves emphasis because it is where money most often gets wasted: do not replace parts on this code speculatively. An intermittent that occurs once a week has an unhelpful property — after fitting a new actuator, a week of normal running feels like proof, and it is not. Unless you found something, the fault has simply not come back yet. Hold out for evidence: a captured event, a visible defect, or a measurement taken while the fault was actually present.

Driveability deserves the same seriousness as the rest of the family, arguably more. A vehicle that runs perfectly and then abruptly loses fuelling is more hazardous than one that runs badly all the time, because nothing warns you. If the intermittent has ever produced a stall while moving, treat the vehicle as unsafe to drive until the fault is found.

Common causes

Loose or low-tension terminal in the metering actuator connector at the injection pump
Corrosion in the pump connector that conducts intermittently as it heats and cools
Heat-hardened, cracked insulation on the pump harness that opens as the engine warms
Chafed wire making and breaking contact against the pump body or a bracket with engine movement
Vibration-fatigued wire strands broken inside intact insulation — an open only under movement
Water intrusion into the connector, conducting or corroding depending on conditions
Fuel gelling in cold weather producing supply restriction that comes and goes with temperature
Marginal lift/transfer pump output that falls below specification only under peak demand
Intermittently sticking metering actuator from deposits or wear
Actuator coil breaking down only when hot — a resistance that reads normal cold and fails at temperature
Poor ground that conducts adequately most of the time and fails under load or vibration

Symptoms

Check engine light that comes on and later goes off by itself, with P0255 stored or pending
Occasional stalling with no warning, then normal running afterwards
Intermittent hard starting with no consistent pattern
Momentary power loss or a brief limp mode that clears on the next restart
Surging or hesitation that appears for a few seconds and then resolves
Fault correlating with rough roads, hard cornering, or engine temperature
Occasional puff of black smoke during an episode
Everything reads normal on a scan tool by the time the vehicle is inspected
Fuel economy slightly worse than expected across a tank despite normal-feeling driving
Commanded and actual fuel quantity briefly diverging in a data log, then re-converging

Diagnostic steps

1.Accept what the code is telling you: the fault is not present right now. Testing components that are currently working will not find it, so plan around capturing the event instead.
2.Read and record the freeze frame in full. Engine speed, load, coolant temperature, vehicle speed, and fuel pressure at the moment of the fault are the most valuable data you have on this code.
3.Look for a pattern in the freeze frame. Hot-only suggests thermal expansion or heat-cracked insulation; cold-only suggests fuel gelling; load-only suggests supply volume or harness movement; rough-road correlation suggests terminal tension.
4.Record all other stored and pending codes, including history codes, since a companion code often localises what the intermittent is affecting.
5.Inspect the pump connector properly — check terminal tension against a matching pin rather than by eye, and look for corrosion, a displaced seal, and evidence of past water intrusion.
6.Follow the pump harness looking for the two intermittent signatures: shiny flattened rub spots, and stiff dark brittle insulation that cracks when flexed.
7.Flex each harness section by hand and watch for a change in a live data parameter or a meter reading.
8.Repeat the wiggle test at full operating temperature, since a cold workshop test reproduces very little of what the fault needs.
9.Data-log commanded versus actual fuel quantity, supply pressure, and actuator feedback through a drive that has historically triggered the fault.
10.Measure fuel supply pressure under peak demand rather than at idle, since a marginal lift pump only falls short when asked for volume.
11.Check fuel quality and drain the water separator, especially if the pattern is cold-weather-only.
12.Test the ground at the pump for low resistance under load, and repeat the test while the harness is being moved.
13.Check manufacturer service bulletins for your engine, since intermittent pump harness and connector faults are exactly the kind of issue that generates bulletins.
14.Do not replace parts speculatively. Wait for a captured event, a visible defect, or a measurement taken while the fault was actually present.

Repair cost

$0 – $1,400

The low end of this range is genuinely zero, because a meaningful share of intermittents on this circuit turn out to be a connector that simply needs to be unplugged, cleaned, and reseated — a repair that costs nothing but time. Diagnosis is the real expense on this code and it is higher than usual, typically $150-$350, because finding an intermittent takes time under the right conditions rather than a quick test. A connector or terminal repair lands at $120-$400. Harness repair for a chafed or heat-damaged section generally runs $200-$650. A fuel filter, if the pattern points at cold-weather gelling, is $60-$220. A lift/transfer pump replacement runs $250-$900. A fuel control actuator is $220-$900 installed on most engines. The important caveat on this code is that money spent on diagnosis is better spent than money spent on parts, because an intermittent that has not returned for a week is not evidence that a new part fixed it.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with diesel injection pump / fuel control actuator service preselected. Adjust labor rate and vehicle category to fit your situation.

Estimate your repair cost

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.