P01DD: Cylinder 10 Injection Timing Performance - Over Retarded

Diesel engines must detect when fuel can no longer be injected at the correct crank angle – CARB requires this for every injector individually, hence one code per cylinder. The start of injection is not measured directly: during overrun with fuel cut-off the control module fires a tiny test injection into one cylinder (GM: about 1.5 mm³) and evaluates the resulting speed change at the crankshaft sensor. From this it learns how much extra energizing time the injector needs (Bosch calls this zero fuel calibration). This code means injector 10 needs clearly more energizing time than intended, i.e. it opens too late – GM sets it above 80 µs of extra time, after two trips. No manufacturer document using the codes for cylinders 9–12 was found; the description follows CARB's requirement and the documented measuring principle (Bosch patent, GM tables for cylinders 1–8). Such codes can only appear on engines with at least that many cylinders.

Cylinder 10 is numbered according to the manufacturer: check your engine's manual before working on it.

Symptoms

• Check engine light on (after two drive cycles)
• Louder combustion noise or knocking
• Rough idle
• Possibly smoke

Most likely causes

• Injector worn, coked or sticking (opens late, delivers too little)
• False setting from software or vehicle vibration (e.g. off-road tyres)
• Wrong injector correction code stored after an injector replacement
• Boost leak or loose injector clamp
• Contaminated fuel

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and wiring of the injector indicated
2. Compare the reading with other engine data while varying the engine speed.
3. Measure the resistance and compare it with the manufacturer's specification
4. Check the control signal with an oscilloscope; on direct injection or diesel engines, leave this to a repair shop because of the high voltages
5. On diesels, check the per-cylinder injection corrections

Good to know

• Repair difficulty: hard
• It affects emissions.

What each character of P01DD means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 1: Air and fuel
• DD: Specific fault in that system

Frequently asked questions

Can I keep driving with code P01DD?

Drive as little as possible and go to a repair shop. If you smell fuel or the engine is shaking badly, do not keep driving.

What causes code P01DD?

The most common causes are: injector worn, coked or sticking (opens late, delivers too little); false setting from software or vehicle vibration (e.g. off-road tyres); wrong injector correction code stored after an injector replacement.

Related codes

• P01DECylinder 10 Injection Timing Performance - Over Advanced
• P0310Cylinder 10 Misfire Detected
• P2B11Cylinder 1 Injection Pulse Offset Exceeded Learning Limit
• P01DBCylinder 9 Injection Timing Performance - Over Retarded
• P01DFCylinder 11 Injection Timing Performance - Over Retarded

Sources

• law.cornell.edu: 13 CCR 1968.2
• patents.google.com: US9109561
• gsi.ext.gm.com: 18OBDG04 Engine Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.