Fuel and air

P01DF — Cylinder 11 Injection Timing Over-Retarded

Severity: medium Drive with care, to a shop

What P01DF means

The ECU compares the actual start of fuel injection in cylinder 11 with the calculated target. P01DF sets when injection begins noticeably later than commanded. It is mostly seen on diesels and engines with many cylinders, where injection timing is monitored for each cylinder separately.

Symptoms

  • Check Engine light on
  • Rough idle or misfire on cylinder 11
  • Reduced power and sluggish acceleration
  • Higher fuel consumption
  • Smoky exhaust or a strong fuel smell
  • Harsh, noisy engine operation

Possible causes

  1. Sticking, worn or dirty cylinder 11 fuel injector
  2. Open circuit, corrosion or poor contact in the injector wiring or connector
  3. Low fuel pressure, weak fuel pump or clogged fuel filter
  4. Valve or injection timing off (stretched chain or belt, misaligned timing)
  5. Faulty camshaft or crankshaft position sensor
  6. Intake air leak distorting the mixture
  7. Software fault or a failed ECU (rare)

How to diagnose

  1. Read all codes and freeze frame data and look for related injector, timing or sensor codes
  2. Review fuel trims and per-cylinder adaptation values
  3. Compare cylinder balance and correction values to confirm cylinder 11 is the outlier
  4. Inspect the injector 11 connector and harness, and check circuit resistance, power and ground
  5. Measure fuel pressure and compare it with specification
  6. Check camshaft and crankshaft sensors and verify engine timing
  7. Look for intake and exhaust leaks
  8. Check for ECU software updates for your model

Common fixes

  • Clean or replace the cylinder 11 injector
  • Repair the injector wiring or connector
  • Replace a faulty crankshaft or camshaft sensor
  • Correct engine timing
  • Update or reflash the ECU; replace it only if confirmed faulty

Questions and answers

What does P01DF mean?

The ECU detected that fuel injection in cylinder 11 starts later than it should. The cause is usually the injector, its wiring, fuel pressure or engine timing.

Can I drive with P01DF?

A short trip to a shop is usually possible, but if the engine loses power or runs rough, stop driving. Extended driving raises the risk of engine and catalytic converter damage.

How do I fix P01DF?

Start with injector 11, its connector and wiring, then check fuel pressure and engine timing. If those are fine, look for an ECU software update.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.