P026D: Fuel Injection Quantity A Higher Than Expected

What it means

Fuel injection quantity A is higher than commanded — often a leaking injector or stuck-open nozzle.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test
• The engine or gearbox may go into limp mode

How it works

The engine control module estimates or monitors fuel injection quantity A and compares it with the amount it commands. This code sets when the delivered or inferred quantity is too high, which can happen if an injector leaks or stays open, fuel pressure is excessive, or injector control is faulty.

Common causes

Most likely first.

1. Injector leaking or stuck open
2. Excessive fuel pressure
3. Injector control fault
4. Fuel pressure regulator problem

Symptoms

• Check-engine light
• Rough running or misfire
• Fuel odor or increased fuel use
• Black exhaust smoke

How to diagnose it

1. Review freeze-frame data and commanded-versus-reported injection quantity A, plus fuel-trim and pressure data, to see when excess fueling occurs.
2. Check for a strong fuel smell, black exhaust smoke, or signs of fuel leakage around the injectors and fuel lines.
3. Inspect injector connectors and control wiring for damage or a short that could keep an injector energized.
4. Check fuel pressure and regulator operation against the manufacturer's specification.
5. Use the specified injector leak or balance test to identify an injector that is leaking or delivering too much fuel.

Common fixes

• Repair a confirmed short or wiring fault in the injector control circuit.
• Replace a leaking or stuck-open injector identified by testing.
• Repair or replace a faulty fuel pressure regulator if pressure testing identifies it.
• Correct excessive fuel pressure or a related supply fault after locating its cause.
• Replace contaminated engine oil if fuel dilution is confirmed, and address the source of the excess fuel.

Can I keep driving?

Avoid driving if there is a strong fuel smell, visible leak, persistent black smoke, or severe misfire; shut the engine off and have the vehicle checked. Excess fueling can dilute engine oil, overheat or damage the catalytic converter, and create a fire risk if fuel is leaking.