Is there an igniter for each coil, or one igniter for the whole engine in a 98 Toyota Avalon? What might it cost to replace it?

Yes, you may have just 3 coils you should change all the spark plugs. Use these pictures to select what yours looks like.




I hope this helps. Take Care.

These are the coils packs Michelle for the Toyota Lexus Avalon Camry Highlander Sienna range.
https://www.amazon.com/ENA-Compatible-Highlander-Replacement-C1175/dp/B00M4GKYRW

Videos that may help

https://www.google.com/search?q=99+toyota+avalon+xls+v6+replace+rear+coil+pack

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P0352 DTC code which refers to a circuit malfunction in the ignition coil , return and install correct coils and if you cant get back plugs changed take it some where to have it done .

Possible causes
Faulty Ignition Coil 1
Ignition Coil 1 harness is open or shorted
Ignition Coil 1 circuit poor electrical connection
Faulty Engine Control Module (ECM)

What does this mean? When is the code detected? Each ignition circuit is continuously monitored by the Engine Control Module (ECM). The test fails when the ECM does not receive a valid pulse signal from the ignition coil. Possible symptoms Engine Light ON (or Service Engine Soon Warning Light) Lack/Loss of Power Engine may be harder to start Engine hesitation Rough engine idle P0351 TOYOTA Description: The ignition system on the vehicle uses individual ignition coils for each cylinder. The Engine Control Module (ECM) controls each ignition coil operation. The ECM sends a ON/OFF signal to energize the ignition coil to create a spark at the spark plug when a spark is required at the cylinder.

The number 1 cylinder is located at the rear left of the engine, looking from front to back of the vehicle.

Vibration while braking usually points towards warped rotors which you will probably have to replace along with pads at the same time. As far as engine performance, you probably want to get a full tune-up. A good tune-up consists of spark plugs, wires(when applicable), induction cleaning service, and a new fuel filter.

check the starter motor

Did he hook it up to the computer. If not he may be guessing and costing you needless money. Get a second opinion it don't cost anything.

a 98 should be a coil/distrubuter all in one. you have to replace whole assembly. cost range for part 70- and up

key is worn down go to a locksmith and have a key cut by code