Fuel and air

P029C — Cylinder 1 Injector Restricted Flow

Severity: medium Drive with care, to a shop

What P029C means

The engine control module noticed, through fuel trim corrections or cylinder balance data, that the cylinder 1 injector is delivering less fuel than commanded. Normally the injector opens for a calculated time and sprays a precise amount of fuel. A clogged nozzle, internal wear or a circuit problem leaves that cylinder running lean. Some sites confuse this code with a turbo underboost condition, but it points to the injector.

Symptoms

  • Check Engine light on
  • Rough idle
  • Cylinder 1 misfire
  • Reduced power and sluggish acceleration
  • Higher fuel consumption
  • Hesitation under load

Possible causes

  1. Clogged or carbon-fouled cylinder 1 injector
  2. Internal injector failure
  3. Open, short or high resistance in the injector circuit
  4. Corroded or damaged connector or wiring harness
  5. Low fuel pressure from a weak pump or clogged filter
  6. Intake air leak causing a lean mixture
  7. Less commonly, a boost pressure problem being misread as this code

How to diagnose

  1. Scan all codes and freeze frame data, noting any misfire codes
  2. Review short and long term fuel trims at idle and under load
  3. Compare cylinder balance and misfire counts on a scan tool
  4. Inspect the cylinder 1 injector connector and wiring
  5. Measure injector resistance and check the drive signal with a scope or noid light
  6. Test fuel pressure and pressure hold
  7. Check the intake for vacuum or air leaks
  8. Swap the injector with a neighboring cylinder and see whether the problem follows it

Common fixes

  • Clean or professionally service the injector
  • Replace the faulty injector
  • Repair the wiring or connector
  • Replace the fuel filter or pump if pressure is confirmed low
  • Fix any intake air leak

Questions and answers

What does P029C mean?

It means the cylinder 1 fuel injector is restricted or not flowing enough fuel. Most often the injector is clogged or faulty, and sometimes the wiring is to blame.

Can I drive with code P029C?

Briefly, yes, but don't put it off. A lean cylinder and misfires can damage the catalytic converter and the engine.

Will fuel injector cleaner fix P029C?

It may help with mild clogging, but it won't fix electrical faults or a worn injector. Diagnose the cause 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.