code 42
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,082
From: So Cal
2023 C4 of the Year Finalist - Unmodified
What year, which engine?
On an L98, Code 42 will set when the Set Timing connector is disconnected to use a timing light to check the timing. When the connector is reconnected, the Service Engine Soon light goes off with the next key cycle. The Code 42 remains for 50 Ignition cycles, but doesn't affect the way the engine runs before it self-clears. << This is probably the most likely scenario for a Code 42 on L98s.
A Code 42 on an LT1 is very likely to be the Ignition Control Module. If you have an LT1 that cranks but does not fire, and there is a Code 42 but no Code 16, it is highly likely that the ICM has failed.
The LT5 also has a Code 42.
Need to know the engine, and perhaps some details, like does it run, or did you just happen to find Code 42 in memory in an L98 after the smog tech checked the timing?
On an L98, Code 42 will set when the Set Timing connector is disconnected to use a timing light to check the timing. When the connector is reconnected, the Service Engine Soon light goes off with the next key cycle. The Code 42 remains for 50 Ignition cycles, but doesn't affect the way the engine runs before it self-clears. << This is probably the most likely scenario for a Code 42 on L98s.
A Code 42 on an LT1 is very likely to be the Ignition Control Module. If you have an LT1 that cranks but does not fire, and there is a Code 42 but no Code 16, it is highly likely that the ICM has failed.
The LT5 also has a Code 42.
Need to know the engine, and perhaps some details, like does it run, or did you just happen to find Code 42 in memory in an L98 after the smog tech checked the timing?
Racer
Joined: Mar 2025
Posts: 494
Likes: 242
Advanced
Joined: Jan 2015
Posts: 62
Likes: 4
From: Surf City USA
What year, which engine?
On an L98, Code 42 will set when the Set Timing connector is disconnected to use a timing light to check the timing. When the connector is reconnected, the Service Engine Soon light goes off with the next key cycle. The Code 42 remains for 50 Ignition cycles, but doesn't affect the way the engine runs before it self-clears. << This is probably the most likely scenario for a Code 42 on L98s.
A Code 42 on an LT1 is very likely to be the Ignition Control Module. If you have an LT1 that cranks but does not fire, and there is a Code 42 but no Code 16, it is highly likely that the ICM has failed.
The LT5 also has a Code 42.
Need to know the engine, and perhaps some details, like does it run, or did you just happen to find Code 42 in memory in an L98 after the smog tech checked the timing?
On an L98, Code 42 will set when the Set Timing connector is disconnected to use a timing light to check the timing. When the connector is reconnected, the Service Engine Soon light goes off with the next key cycle. The Code 42 remains for 50 Ignition cycles, but doesn't affect the way the engine runs before it self-clears. << This is probably the most likely scenario for a Code 42 on L98s.
A Code 42 on an LT1 is very likely to be the Ignition Control Module. If you have an LT1 that cranks but does not fire, and there is a Code 42 but no Code 16, it is highly likely that the ICM has failed.
The LT5 also has a Code 42.
Need to know the engine, and perhaps some details, like does it run, or did you just happen to find Code 42 in memory in an L98 after the smog tech checked the timing?
Thanks for the reply.
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Joined: Jan 2015
Posts: 62
Likes: 4
From: Surf City USA
