I have been detailing the engine compartment on my car and removed the battery so I could get the entire tray area cleaned up. I put the battery back in and called it a day. This was 2 weeks ago. This past weekend, I started the car and got the dreaded Check Engine light. I pulled code 42. I decided to disconnect the battery again and left it off for 24 hours. I still get the code on restart. The car really didn't run that great. It seems like I had 75% power. What should I start with? I tried researching the code on here and see most responses are tied to cars that have been around the block a few times. Mine hasn't even made it around the block once yet!!

BTW, last year, I replaced the ignition module when I replaced the fuel pump and a few other parts. I still have the original part and can put it back in for testing. Thanks for any advice or direction.

 

Here's what I found online with a quick google......Should be able to find a trouble shooting guide about the code somewhere on line or here.


Diagnostic Trouble Codes - 1987
Chevrolet

12 No Reference Pulse 13 Oxygen Sensor Circuit 14 Coolant Sensor Shorted 15 Coolant Sensor Circuit Open 21 Throttle Position Sensor (TPS) (Signal Voltage High) 22 Throttle Position Sensor (TPS) (Signal Voltage Low) 23 Mixture Control (M/C) Solenoid Voltage Low 24 Vehicle Speed Sensor (VSS) Circuit 32 BARO Sensor Voltage Low 34 Differential Pressure (VAC) Sensor - Voltage Incorrect 41 No Distributor Reference Signal 42 Electronic Spark Timing (EST) or Bypass Fault 43 Electronic Spark Control (ESC) Voltage Low to ECM 44 Oxygen Sensor Circuit (Lean Exhaust Indication) 45 Oxygen Sensor Circuit (Rich Exhaust Indicated) 51 PROM Error 53 Exhaust Gas Recirculation (EGR) Control Error 54 Mixture Control Solenoid (M/C) Voltage High

 

I've been looking in all the wrong places....I decided to check the battery terminal connections and start looking at all wiring connections. It appears that at some point during my detailing, I inadvertantly disconnected the EST By-pass connector at the cowl. I hooked it up again and the code is gone. Next time, I'll look for the obvious before wasting peoples time! Thanks anyway.