P0355 OBD-II: Ignition Coil "E" Primary/Secondary Circuit

OBD II Fault Code

• OBD II P0355 Ignition Coil "E" Circuit Malfunction

The ignition coil or coils are responsible for igniting the air/fuel mixture inside the combustion chambers. Without reliable performance from the ignition coil(s) the vehicle will stumble and misfire.

Code P0355 indicates there's an electrical problem in either the primary ( the computer side ) or the secondary ( the spark plug side ) of the Ignition Coil "E" Circuit.

P0355 Symptoms

• Check Engine Light will illuminate
• Engine idles rough
• Engine misfires on acceleration
• In rare cases, the engine may not exhibit noticeable symptoms

Common Problems That Trigger the P0355 Code

• Defective Ignition Coil(s)
• Defective Spark Plug(s)
• Intake Manifold Vacuum leaks
• Carbon buildup in the Throttle Body air passages
• Defective Idle Air Control Valve or Electronic Body

Common Misdiagnosis

• Ignition coil(s) replaced when cause of the malfunction was a vacuum leak
• Spark Plugs replaced when cause of the malfunction was a vacuum leak

P0355 Diagnostic Theory for Shops and Technicians

When the code P0355 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is not seeing the proper electrical signals from the ignition coil(s) during normal operation. This can be caused by problems on either the primary (computer) side or the secondary (spark plug boot, spark plug wire and/or spark plug itself ) side.

When diagnosing a P0355 code, it is important to record the freeze frame information and then to duplicate the code setting conditions with a test drive. Pay close attention to the engine load, throttle position, RPM, and road speed. Road test the vehicle while viewing the misfire PID information on a data streaming scanner. If the vehicle is misfiring then you may have verified code P0355. Be sure to verify the the steadiness of the crank signal, because this can cause all kinds of downstream problems. If the vehicle deploys a multiple direct coil ignition system, locate the offending coil. Switch the entire coil and spark plug as an assembly with a known good cylinder, Clear the code(s) and go for a test drive. If the code re-sets and follows the coil assembly that was moved, then you may have verified the cause of the P0355 code. If the same cylinder sets the code, then perform a compression test on the offending cylinder and check for any vacuum leaks in its area with a good quality smoke machine. If the compression and smoke test results are good, then check the connector and wiring for that cylinder's coil circuit. If the connector and circuitry are good, then test the coil firing signal with a labscope, because the coil driver circuit may be defective.