See also:

Intermittent Problems

Note: Prices are subject to change.

Vehicle's number of cylinders can affect prices.

Do you have a noise that comes and goes, or an intermittent problem that goes away for a while only to return later? The difficulty in repairing an intermittent problem is twofold:

  1. Duplicating the condition.
    Most problems cannot be solved without recreating the defect. Example; A fuel pressure regulator is intermittently allowing fuel pressure to go from 40 PSI to 70 PSI causing a rich running condition with the engine running poorly and blowing black smoke out the tailpipe. The difficulty here is that if a fuel pressure gauge is used to check the regulator, it will not show a problem unless the condition exists at that time. This comes down to either being lucky enough to have the problem occur at the right time or in monitoring the system for as long as it takes for the condition to occur, whether it takes minutes, hours, or days. Most customers are not happy with an estimate that is large enough to cover any of these possibilities.
  2. Ensuring the problem is solved.
    How do you know the condition is gone for good? Example from above; The fuel pressure regulator is suspected, so it is replaced with a new part. The vehicle is test driven for a total of an hour over a period of several days and the condition does not occur. Is the problem solved? What if the problem returns after a week or so?


  1. Wait until the problem gets worse.
    When the condition is occurring regularly, IE; several times per mile or in a 10 minute period, it can be diagnosed more easily and checked properly after repair.
  2. Start replacing parts.
    If cost is no object, one can start replacing suspect parts. You still need a solution to "Ensuring the problem is solved", see above.

With the above difficulties in mind, you can see why we cannot guarantee diagnosis or cures for an intermittent problem.