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1998 Chevrolet Cavalier 2.4L P0018 Fault: Check Engine Light, Cold Start Issues, and Emissions Troubleshooting

Model: 98 Chevy Cavalier Fault Code: P0018 Posted: 2016-08-17 13:43

The check engine light has come on in my 1998 Chevrolet Cavalier with a 2.4L engine, and the diagnostic scan shows fault code P0018. I replaced the coolant temperature sensor as recommended by AutoZone, but the check engine light returned shortly after. The vehicle exhibits cold start behavior where it requires pressing the gas pedal to get moving—only after which it runs smoothly. If I don't press the gas or wait for the engine to stabilize, it will stall. Additionally, the dashboard thermostat gauge is not reading correctly. What should I check next? Is P0018 common on this model year and engine configuration? Are there any reliable methods to pass emissions testing without replacing major components? I suspect a sensor or wiring issue but need confirmation on which parts are involved.

Related fault codes
P0018
Comments (5)
Anonymous 2016-08-17 15:03

First, could you clarify which sensor you replaced and why? P0018 is not typically caused by a simple temperature sensor failure—it's more likely related to a timing or signal discrepancy between the CKP (crankshaft position) and CMP (camshaft position) sensors. These sensors must agree on Top Dead Center (TDC). Confirm that your vehicle is indeed a 1998 model, and check the eighth character of the VIN—this will help identify the exact engine variant (e.g., 2.4L vs. 2.2L).

Anonymous 2016-09-05 13:30

I replaced the coolant temperature sensor as advised by AutoZone's diagnostic tool, which flagged it as the source of P0018. However, after installation, the check engine light returned within minutes. The dashboard thermostat gauge is also not showing any readings—this suggests a potential issue with either the sensor or its wiring.

Anonymous 2016-09-05 13:34

The eighth character of my VIN is '4'.

Anonymous 2016-09-05 14:32

I'm trying to confirm: 1998 Chevrolet Cavalier, VIN ending in '4', P0018. Is this a 2.2L engine? The VIN character '4' typically indicates a 2.2L variant—could this be a misdiagnosis? Also, P0018 is not commonly listed in standard fault code references for this model; it may actually be P0118 (coolant temperature sensor high voltage). Could the issue be related to that instead?

Anonymous 2016-09-05 17:54

The 1998 Chevrolet Cavalier with VIN ending in '4' is typically a 2.2L engine, not 2.4L. If you're seeing P0018, it may actually be a misdiagnosis—P0118 (coolant temperature sensor high voltage) is more common and relevant for this model. You replaced the coolant temperature sensor? Check for faulty wiring connections, open circuits in the signal wire, or poor grounding. A proper circuit test would be needed to confirm the root cause.