Fuel and air

P01DA — Cylinder 8 Injection Timing Over-Advanced

Severity: medium Drive with care, to a shop

What P01DA means

The engine control module compares the actual start of fuel injection in cylinder 8 with the commanded timing. P01DA sets when injection begins earlier than allowed, meaning timing is over-advanced. This is an uncommon code, mostly tied to GM vehicles, and sources describe it differently, so confirm the fault with testing before replacing parts.

Symptoms

  • Check Engine light on
  • Rough idle
  • Reduced engine power
  • Misfire or hesitation under acceleration
  • Poor fuel economy

Possible causes

  1. Faulty or sticking cylinder 8 fuel injector
  2. Damaged wiring or a poor connection in the injector control circuit
  3. Fuel supply problem such as low pressure, weak pump or clogged filter
  4. Air leak that shifts the air-fuel mixture
  5. ECM software fault that needs an update
  6. Mechanical problem in cylinder 8 (rare)

How to diagnose

  1. Scan all codes and freeze frame data, and look for related injector, misfire or fuel system codes
  2. Check fuel trims and adaptation values and compare cylinders
  3. Inspect the cylinder 8 injector connector and harness for corrosion, chafing or a loose fit
  4. Test the injector circuit: power, ground, coil resistance and the ECM control signal
  5. Measure fuel pressure and compare it to the factory spec
  6. Check the intake and exhaust for leaks
  7. Run a cylinder balance test or injector kill test to find the weak cylinder
  8. Check for ECM software updates for your vehicle

Common fixes

  • Replace or clean the cylinder 8 injector
  • Repair the injector wiring or connector
  • Fix the cause of low fuel pressure, such as a filter or pump
  • Repair intake or exhaust leaks
  • Update or reflash the ECM

Questions and answers

What does P01DA mean?

The ECM found that fuel injection in cylinder 8 starts too early. The cause may be the injector, its wiring or a fuel system problem.

Can I drive with P01DA?

Limited, careful driving to a shop is usually possible. If the engine misfires or shakes, stop to avoid damaging the catalytic converter.

Will clearing the code fix it?

No. If the cause remains the code will return. Check the injector, its wiring and fuel pressure first.

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.