P2DDD: Fuel Injection Quantity C Higher Than Expected

What it means

The measured fuel injection quantity for group C is above the calibrated window. Injector flow drift, rail pressure off, or measurement bias.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The engine control module estimates how much fuel injection group C delivers and compares it with a calibrated range. This code sets when group C's measured quantity is higher than expected, which can result from excess injector flow or excessive rail pressure.

Common causes

Most likely first.

1. Injector leaking
2. Fuel rail pressure high

Symptoms

• Check-engine light
• Rough running or misfire
• Reduced fuel economy
• Fuel odor or dark exhaust

How to diagnose it

1. Record freeze-frame data and check live fuel-quantity and misfire data to see when group C exceeds its expected range.
2. Inspect group C injector connectors and wiring for damage or poor contacts that could distort injector control.
3. Check for fuel odor, visible leaks, dark exhaust, and other signs of excess fuel before running further tests.
4. Measure fuel rail pressure under the conditions indicated by the freeze frame and compare it with the manufacturer's specification.
5. If pressure and wiring are sound, test group C injectors for leakage or excess flow using the manufacturer's procedure.

Common fixes

• Repair damaged or poorly connected group C injector wiring.
• Correct a fuel-pressure control fault if rail pressure is above the manufacturer's specification.
• Replace a leaking group C injector identified by testing.
• Verify group C fuel-quantity data and exhaust behavior after the repair.

Can I keep driving?

Avoid extended driving if there is a strong fuel smell, dark exhaust, rough running, or a flashing check-engine light; excess fuel can raise emissions and damage the catalytic converter. Stop and address any visible fuel leak promptly.