| Subject: | LC3 4.4L Supercharged Engine Hard Start, Miss, Misfire, Idle Rough, MIL/SES Light, DTCs P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308 Due to Fuel Fouled Spark Plugs (Replace Spark Plugs)
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| Models: | 2006-2009 Cadillac STS-V, XLR-V | |
| with Northstar® 4.4L Supercharged V8 Engine (VIN D — RPO LC3) |
Some customers may comment on a hard start condition, rough idle, miss and or misfire with the MIL/SES light illuminated.
Upon further investigation, technicians may find DTCs P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308.
This may be experienced on vehicles that have repeatedly been driven short distances without reaching operating temperature. This condition is most likely to occur when the vehicle is still a dealer stock unit or when the vehicle arrives at the dealership on the transporter. This condition may also occur if the car is driven for short duration trips.
This condition may be caused by the engine not reaching operating temperature before turning off the ignition.
To avoid this condition, run the engine until the coolant reaches operating temperature. DO NOT attempt to clear fouled spark plugs by running the engine at a higher RPM – doing so may damage the catalytic converters.
Spark plugs that are still fouled should be replaced with P/N 12592619. Refer to Spark Plug Replacement in SI. Clear any DTCs stored in the ECM.
Important: In order to prevent a reoccurrence, allow the engine to reach operating temperature before turning off the engine and returning the vehicle to the customer.
| Part Number | Description |
|---|---|
| 12592619 | Spark Plugs, (A/C DELCO® #41-991) Platinum Plug |
| 12345579 (U.S) 10953481 (Canada) |
Dielectric Silicone Grease |
Article ID: 128
Created: January 7, 2020
Last Updated: June 20, 2022
Author: Rob Loszewski
Online URL: https://www.xlr-net.com/knowledgebase/article/2006-2009-cadillac-xlr-v-service-bulletin-08-06-04-038-lc3-4-4l-supercharged-engine-hard-start-miss-misfire-idle-rough-128.html