Fuel and air

P027E — Cold Start Fuel Injection Quantity Lower Than Expected

Severity: medium Drive with care, to a shop

What P027E means

The engine control module calculates how much fuel a cold engine needs and monitors the mixture with the oxygen sensors. P027E sets when fuel delivery on a cold start is lower than expected or the mixture runs too lean. Common culprits are injectors, fuel pressure, or the sensors the ECM uses to calculate injection.

Symptoms

  • Check engine light on after a cold start
  • Rough idle while the engine is cold
  • Hesitation or weak acceleration
  • Misfires during the first minutes of running
  • Long or hard cold starting
  • Higher fuel consumption

Possible causes

  1. Clogged or faulty fuel injector
  2. Low fuel pressure from a weak pump, bad regulator or clogged filter
  3. Faulty coolant temperature sensor causing wrong cold enrichment
  4. Vacuum leak or faulty MAF sensor
  5. Damaged wiring or corroded connector at the injector
  6. Rarely, an ECM software or calibration issue

How to diagnose

  1. Scan all codes and freeze frame data, and note any related lean or misfire codes
  2. Compare the coolant temperature reading on a cold engine with actual temperature
  3. Review short and long term fuel trims when cold and warm
  4. Measure fuel rail pressure at start-up and after shutdown and compare to specification
  5. Check the intake for air leaks and inspect the MAF sensor
  6. Inspect injector connectors and harness, and check power and control signals
  7. Test the injectors for resistance, balance and leakage, and clean if needed
  8. Check for an ECM software update for your model

Common fixes

  • Clean or replace faulty injectors
  • Repair injector wiring and connectors
  • Replace the fuel filter, pump or pressure regulator if pressure is low
  • Replace a faulty coolant temperature or MAF sensor
  • Fix intake air leaks
  • Update the ECM software

Questions and answers

What does P027E mean?

It means the ECM detected too little fuel or a lean mixture during a cold start. Check the injectors, fuel pressure and related sensors.

Can I drive with code P027E?

Short trips are usually possible, but don't put it off. A lean mixture can cause misfires and damage the catalytic converter and engine.

Why does P027E only show up when the engine is cold?

A cold engine needs a much richer mixture, so any weakness in fuel delivery or a wrong temperature signal shows up more. Symptoms often fade once the engine warms up.

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.