OBD1 Code 42

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Aug 4, 2025 | 03:28 PM

John@scc

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Joined: Jan 2015

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From: Surf City USA

OBD1 Code 42

Hey guys,

I have a Code 42 on my 1982 Corvette, which indicates a faulty EST (Electronic Spark Timing). Another source I found says faulty wiring between Ignition Module and ECM.

Has anyone else experience this issue and what was the fix? I'm wondering if my ignition module might be going bad.

Thanks in advance.

Aug 4, 2025 | 08:11 PM

Fly skids up!

Melting Slicks

Joined: May 2021

Posts: 2,261

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From: Fleming Island, FL

Did you forget to reconnect the EST plug after checking the timing? That would be the most common answer. However it gets complicated after that. There's are many reasons for code 42, more than a simple form answer. What you need is the factory service manual which has a flow chart that will guide you through the diagnostics.

Aug 4, 2025 | 08:57 PM

John@scc

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From: Surf City USA

I didn't do a timing test. The Check Engine light just came on itself a couple days ago, then it went off and now back on. So when I tested with a paper clip, I got 4 flashes then 2.

Is it possible the EST plug came loose? Where do I find the EST plug?

Aug 4, 2025 | 09:26 PM

Fly skids up!

Melting Slicks

Joined: May 2021

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From: Fleming Island, FL

It's a single wire weather pack connector near the distributor with a brown wire.

Aug 5, 2025 | 06:21 AM

John@scc

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From: Surf City USA

Quote:

Originally Posted by Fly skids up!

It's a single wire weather pack connector near the distributor with a brown wire.

I have not seen one of those, but I'll look again for it.

Thanks for the reply.

Aug 5, 2025 | 11:09 AM

John@scc

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From: Surf City USA

Quote:

Originally Posted by Fly skids up!

It's a single wire weather pack connector near the distributor with a brown wire.

I have 2 different brown wires.

Aug 5, 2025 | 11:15 AM

MelWff

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Buy this book and follow the code diagnostics.
https://www.zip-corvette.com/82-shop...ce-manual.html

Aug 5, 2025 | 11:32 AM

Fly skids up!

Melting Slicks

Joined: May 2021

Posts: 2,261

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From: Fleming Island, FL

It's the one in the first picture and it's connected. You'll need the FSM for this one.

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Aug 5, 2025 | 11:47 AM

Eric P

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Joined: Aug 2019

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Module , wiring or computer, back in the day we used to install a lot of modules for that code. it's cheap and easy enough to try and you're not out much money if it doesn't fix it