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1998 Cadillac Eldorado P0121 Code: Fast Idle Issue and Causes

Model: 1998 Cadillac Eldorado Fault Code: P0121 Posted: 2007-09-15 07:21

I recently encountered a P0121 diagnostic trouble code on my 1998 Cadillac Eldorado. When this code appeared, the engine would exhibit an abnormally high idle speed. I managed to clear both the code and the fast idle behavior by turning off the engine and restarting it. Since then, the issue has not reoccurred. While the problem seems intermittent, I'm seeking clarification on what could be causing the P0121 code and whether this indicates a serious underlying issue that requires repair.

Related fault codes
P0121
Comments (2)
Anonymous 2007-09-15 07:47

The P0121 code typically points to a throttle position sensor (TPS) fault, which is indeed a concern. A persistent check engine light and erratic idle behavior can affect vehicle performance and safety, so it's important to address this issue promptly.

Anonymous 2007-09-16 00:16

Hi! Check the throttle position sensor harness and all wire connections for corrosion, loose fittings, or physical damage. A poor connection in the TPS wiring can trigger the P0121 code and cause idle instability.