Ignition

P030A — Ignition Coil A Control Circuit Open

Severity: medium Drive with care, to a shop

What P030A means

The engine control module monitors the circuit it uses to command ignition coil A (or its built-in driver). If it doesn't see the expected response, as with a broken wire, poor connection or failed coil, it sets P030A and turns on the check engine light. Exact circuit details vary by manufacturer, so confirm the wiring for your vehicle.

Symptoms

  • Check engine light on
  • Rough or unstable idle
  • Engine misfire
  • Reduced power and sluggish acceleration
  • Worse fuel economy
  • Hard starting

Possible causes

  1. Failed ignition coil A
  2. Open or damaged wiring in the coil control circuit
  3. Corroded, loose or broken coil connector
  4. Missing power or ground at the coil
  5. PCM or ignition driver fault (uncommon)

How to diagnose

  1. Scan all codes and freeze-frame data, and look for related misfire codes (P030x).
  2. Inspect coil A's connector and harness for chafing, corrosion or a poor fit.
  3. Swap coil A with a neighboring coil and see whether the code or misfire follows.
  4. Use a multimeter to check power and ground at the coil connector with the ignition on.
  5. Test the control wire from the coil connector to the PCM for opens and shorts.
  6. Measure coil resistance and compare it with the manufacturer's spec.
  7. If the wiring and coil are good, check the PCM and its power supply.

Common fixes

  • Replace the faulty ignition coil
  • Repair the damaged wire or harness section
  • Clean, tighten or replace the connector
  • Replace or reflash the PCM if confirmed as the cause

Questions and answers

What does P030A mean?

The PCM found an open or missing signal in the control circuit for ignition coil A. The coil, wiring or connector is usually to blame.

Can I drive with P030A?

Only briefly and carefully, such as to a shop. Misfires can damage the catalytic converter and hurt fuel economy.

How can I quickly test the coil?

Swap it with a neighboring coil and clear the code. If the fault follows the coil, replace it; if not, look at the wiring.

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.