heteroskedasticity plot

to check my model for heteroskedasticity I want to plot the fitted values and the residuals (plot (fitted.values (model), residuals (model)).
But then I always get this error message: Error in match.arg(plot) :
'arg' must be NULL or a string vector
Does anyone know why this is happening and how to fix it?
Thanks a lot!

If you are using lm()

fit <- lm(mpg ~ drat, data = mtcars)
plot(fit,which = 1)

Created on 2023-03-06 with reprex v2.0.2

Other models may have different methods

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[quote="technocrat, post:2, topic:161429"]

Technocrat, what does 

which = 1 

do here?

The plot.lm method called by plot() produces six plots and by default four are displayed interactively with prompts. To choose the which flag can be used. Often, a four pane window option is set to show the four defaults in one go.

fit <- lm(mpg ~ drat, data = mtcars)
op <- par(mfrow = c(2,2))

#> null device 
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