Lexus LS400 Rough Idle

Learn if it's a simple fix or time to seek out a trusted technician.

What are common reasons my Lexus LS400 has a rough idle?

While there are a variety of reasons your Lexus LS400 has a rough idle, the most common 3 are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
of the time it's
Vacuum Leak
of the time it's
Spark Plugs
of the time it's
Ignition Coil

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Related Lexus LS400 Questions

See what others are asking about their Lexus LS400. Get answers from RepairPal's community of auto experts and enthusiasts.
Car starts normally. no colored smoke from exhaust.
When i turn on the a/c the eng rpms go up, and makes the car idle rough.

Related Lexus LS400 Problems

Find the most common driver-reported problems that are to blame when a Lexus LS400 has a rough idle.
Owners have reported experiencing rough deceleration, inability to engage overdrive, and a check engine light with di...
Lexus LS400 Repairs and Prices
All costs based on RepairPal Fair Price Estimate™ averages. Actual prices may change depending on final diagnosis.

Lexus LS400 Rough Idle Repair Symptoms

A failing ignition coil will create misfires in the engine, and lead to hesitation, extreme power loss, engine stalling, poor fuel mileage, and illumination of the check engine ...Read More
As we discussed, spark plugs are necessary for any gasoline engine to run. When they fail, the engine is in a constant state of attempting to ignite air and fuel, but cannot. Th...Read More