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P0300 and P0742 Diagnosis: 2000 Chevrolet Cavalier with Automatic Transmission and 74,000 Miles

Model: chevy cavalier Fault Code: P0300 Posted: 2006-12-03 12:05

I own a 2000 Chevrolet Cavalier (2.2L engine, automatic transmission, 74,000 miles) and recently experienced a check engine light. A diagnostic scan revealed two fault codes: P0300 (random/multiple cylinder misfire) and P0742 (torque converter circuit stuck on). The vehicle was previously running rough, eventually stalling completely. I replaced the fuel filter and used injector cleaner, but symptoms worsened. Subsequent replacement of spark plugs and ignition wires did not resolve the issue. Upon inspection, one coil pack showed a corroded terminal—after replacing it, the vehicle failed to start at all. Reinstalling the original coil pack also resulted in no spark. Currently, only one cylinder (the un-replaced coil pack) produces a spark; both the replaced and original coil packs show no spark. This suggests either a faulty ignition module or wiring issues. I suspect the power supply to the coils may have been intermittently present due to corrosion but is now completely absent. While the P0300 code points to misfiring, the presence of P0742 raises concerns about transmission control—though it has not yet been addressed. I’ve already replaced the spark plugs, wires, coil packs, and ignition control module (ICM). I am now attempting a battery disconnection to reset the powertrain control module (PCM), hoping this will trigger a relearn cycle. However, if no spark persists across cylinders 1 and 4, the issue may lie in the PCM’s signal delivery or grounding. I’m seeking advice on how to diagnose potential wiring faults, check cam/crankshaft signals, and evaluate power/ground connections to the ignition module. Any insights into whether P0742 could be contributing to the misfire or stalling would also be greatly appreciated.

Related fault codes

P0300P0742

Comments (7)

Anonymous 2006-12-03 13:45

Here are two detailed images related to P0300 troubleshooting. Clicking on them will expand and display the text clearly. These may help visualize common diagnostic steps for random misfires in older GM engines.

Anonymous 2006-12-04 12:51

The ignition module (ICM) that the coil packs connect to should be inspected, especially since it's a common source of failure in 2000 Chevrolet Cavalier quad-4 engines. A faulty ICM can cause intermittent spark and misfire symptoms.

Anonymous 2006-12-04 13:20

We recently replaced the ignition module and managed to get the engine to start briefly, but one spark plug wire was arcing at the coil pack—this caused a short. We crimped the connection securely. After that, it ran for about two seconds before stalling again. The issue may still be related to wiring or signal integrity. Thanks for the reference images—they were helpful, though we don’t have all the tools needed to perform full diagnostics.

Anonymous 2006-12-04 13:43

Some GM vehicles, especially those with older PCM systems, can struggle to relearn idle speed after a reset—particularly if the battery was discharged or the computer was cleared. Once running, does giving it throttle keep it from stalling? This could indicate an idle control issue.

Anonymous 2006-12-04 16:10

I tried applying throttle and the engine still stalled. It also produced loud, abnormal noises that are difficult to describe in text—similar to a rough, metallic knocking or sputtering. After flooding the fuel tank (likely due to poor combustion), I waited about 45 minutes before trying again with no improvement. I’ve since decided to replace the spark plug wires tonight as a last step. If that doesn’t work, I’ll inspect the PCM by smell and check for burnt components tomorrow. Thanks for your input—any further suggestions would be appreciated.

Anonymous 2006-12-05 11:43

The vehicle still won't start at all. One additional detail: during the initial diagnostic, P0742 (torque converter circuit stuck on) was also detected—but I initially dismissed it as unrelated. Now I'm wondering if this could be contributing to engine instability or misfire symptoms. Currently, there is no spark on cylinders 1 and 4. All components—spark plugs, wires, coil packs, and ignition control module (ICM)—have been replaced. I’m now attempting a battery disconnection to reset the PCM, hoping it will trigger a relearn sequence.

Anonymous 2006-12-05 18:17

At this stage, I recommend checking the camshaft and crankshaft position sensor signals, as well as verifying all power and ground connections to the ignition module. A loss of spark across multiple cylinders may stem from faulty signal input or poor grounding in the ignition system.