Diagnostic Trouble Code-Ignition Signal


What is the Circuit like?

  • A ground for the electronic spark timing 1 circuit is enabled by the engine control module (ECM).
  • The magnetic field created by the coil collapses when the ECM removes the ground path of the ignition primary coil.
  •  This dying magnetic field generates a voltage in the secondary coil which shoots the spark plug.
  • A close monitoring is done to the circuit between the ECM and the electronic ignition system for an open circuit, short to voltage, and low voltage.
  • DTC PO351 is introduced the moment the ECM sniffs a problem in the spark timing 1 circuit.

What leads to the Setting of DTC?

·   This DTC can be stored in "key-on" status.

·   Time of fault fall occurrence is > time of the DIS fall occurrence.

·   Must receive more than 40 failures within 80 test cycles.

What happens when DTC sets?

When will DTC clear?

1) The Malfunction Indicator Lamp (MIL) will illuminate.


1) The MIL will turn off after four repetitive ignition cycles in which the diagnostic runs without a fault.


2) The ECM will record operating conditions at the time the diagnostic fails which will be stored in the Freeze Frame and Failure Records will buffer.


2) A history DTC will clear after 40 consecutive warm-up cycles without a fault.


3) A history DTC is stored.


3) DTC(s) can be cleared by using the scan tool.



4) Dissociating the ECM battery feed for more than 10 seconds.



Diagnostic Tools

Check and correct any abnormal engine noise before using the diagnostic table.


Any circuitry that is suspected as causing engine noise complaint should be thoroughly checked for the following conditions:

·   Backed-out terminals.

·   Improper mating.

·   Broken locks.

·   Improperly formed.

·   Damaged terminals.

·   Poor terminal-to-wire connections.

·   Physical damage to the wiring harness.

DTC P0351 - Ignition Signal Coil A Fault



Task Done? (Yes)

Task Done?



Perform (EOBD) System Check.


Go to Step 2

Go to "On-Board Diagnostic System Check"


Survey for a faulty connection or a damaged


terminal 1 at the ignition coil.




Go to Step 8



Go to Step 3


Check for a faulty connection or a damaged terminal 31 at the engine control module (ECM) connector.


Go to Step 8

Go to Step 4


  1. Take the ignition switch to LOCK.
  2. Disconnect the ECM.
  3. Examine the ignition control circuit for a short to ground.


Go to Step 8

Go to Step 5


Check the ignition control circuit for a short to battery voltage.


Go to Step 8

Go to Step 6


Watch out for an open in the ignition control.


Go to Step 8

Go to Step 7


Substitute the ECM.


Go to Step 8



Clear the Diagnostic Trouble Codes (DTCs) by means of a Scan Tool.

1) Start the engine and Idle at normal operating temperature.

2) Run the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has been run and passed?

Go to Step 9



Check if any additional DTCs are set.


Are any DTCs displayed that have not been diagnosed?

Go to Applicable DTC table

The System  of your car is OK