Ignition

P035B — Ignition Coil E Control Circuit Low

Severity: medium Drive with care, to a shop

What P035B means

The engine control unit switches current to the primary winding of ignition coil E and monitors that control circuit. P035B sets when the signal voltage or current is lower than expected, meaning the coil is not getting a proper command or the circuit has a fault. The result can be a weak or missing spark in that cylinder. Which cylinder coil E serves depends on the manufacturer, so check the wiring diagram for your engine.

Symptoms

  • Check engine light on
  • Misfire or rough running
  • Shaking at idle
  • Reduced power and sluggish acceleration
  • Hard starting or stalling
  • Higher fuel consumption

Possible causes

  1. Failed ignition coil or coil pack
  2. Damaged or corroded control-circuit wiring
  3. Poor connection or corrosion at the coil connector
  4. Open circuit or short to ground in the control wire
  5. Faulty ignition module or ECU driver (uncommon)
  6. Low coil supply voltage from a bad ground or blown fuse

How to diagnose

  1. Read all codes and freeze-frame data and look for related misfire codes
  2. Identify which cylinder coil E serves using the diagram for your engine
  3. Inspect the coil connector and harness for heat damage, corrosion, chafing and loose fit
  4. Swap coil E with a known good coil and see whether the misfire or code follows
  5. Check power and ground at the coil connector with a multimeter
  6. Check the control signal from the ECU with a scope or test light
  7. Test the control wire to the ECU for opens and shorts
  8. If the wiring is good, test the ignition module or ECU

Common fixes

  • Replace the faulty ignition coil
  • Replace worn spark plugs if they damaged the coil
  • Repair damaged wiring or replace the connector
  • Clean the terminals and restore the ground connection
  • Replace the ignition module or repair/replace the ECU if confirmed faulty

Questions and answers

What does P035B mean?

It means a low signal in the control circuit of ignition coil E (coil B). The ECU does not see a normal control signal, so the cylinder may lose spark.

Can I drive with P035B?

Only briefly and gently. Misfires can damage the catalytic converter, and a flashing check engine light means you should shut the engine off.

How can I quickly test the coil?

Swap it with a coil from another cylinder and clear the codes. If the misfire follows the coil, the coil is bad. If not, look at the wiring, connector or ECU.

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.