Check Engine Light and Codes

I have a 2001 Toyota Camry and recently ck. engine light came on as was reset and came on again. Codes that are revealed are P0300, PO301. compression test = 175. Just did the 120,ooo mile service and new plugs were put on - however they are saying that all they can find is a random miss fire on 1 and see a small nick on spark plug wire and suggest replacing plugs and wires. Does this sound correct - even though spark plugs were just replaced at Toyota 120,000 mile service? The engine hesitates when idiling in park, drive, reverse and neutral and sometimes does not take off smooth when take off at stop light after idiling. Thanks for any help and information you can give. Peace and Light - Mary Frances

For the compression test you should have 4 or 6 numbers (one for each cylinder) - or do you mean that cylinder 1 was at 175? Find out and post the info.

If the plugs were just replaced, then there is no need to put new ones in - though they are not expensive. I would at least pull them, check out how they look and check the gap. If there is any reason at all to suspect the wires, then replacement is a good idea. So if I were you I’d be likely to just have new wires put on.

While P0301 is cylinder 1, P0300 indicates random and/or multiple cylinder misfire. This could come from degraded spark plug wires, but has anyone checked anything else - such as fuel injectors? If a new set of wires, and a good check of the new plugs doesn’t yield any solution, the rest of the ignition system needs to be checked along with the fuel system operation.

First, unless you are over 124K miles, plug replacement should be covered under your 3 mos/4K mi standard warranty most mechanics work comes with. Are the current mechanics the same ones who did the 120K warranty work? If so, tell them you expect any defective plug replacement to be free, unless you are outside their parts and labor warranty. Unless something went badly wrong with the plug installation, plugs last 30K miles easily. Do they know the plugs are relatively new?

At your mileage I can understand the plug wire replacement, but they may still be shooting in the dark.

A poor take off from idle when you accelerate might also suggest a fuel delivery prblem, but more diagnosis is needed before I would jump to that conclusion.

Ask them if your car is making it to a driveability specialist or is it being worked on by a lower level beginning tech. Has the shop foreman gotten involved with your cars problem? Is he sure he has the right man with the right training to do the job?

Ask how complete a diagnosis they are doing. Are they saying no clues from any of the fields displayed by their scan tool are present? Have they use a ocilloscope to look at the secondary ignition system (plug wires and plugs) performance?

With the scan tool you can look at just what codes are present or you can also look at a wealth of information about the cars fuel control system,they must know how to use their multimeters and a lab scope,no reason for guessing.