Q: I have been working on a lexus ES350 I'm getting codes p0300 p0174 and c342d and can't figure out what the problem is, can u help?

asked by on October 31, 2017

It started as code p0301 so I replaced cool on cylinder 1 and all spark plugs and boots since it was such a big job having to take intake off to access cylinders 1,3, &5. Then had to go back and fix camshaft position sensor bc of one wire pulling loose. And still getting code p0300 along with p0171 so I replaced pcv valve bc it had a small leak and I'm still getting codes p0300, p0141, p0355 and also this code c342d. Please help...
My car has an automatic transmission.

C342d relates to faults in the throttle position sensor (TPS) or the idle air control valve (IAC). Check the wiring to the TPS sensor and the IAC valve and test for high resistances which will show up as voltage drops. P0355 can be caused by wiring faults but also by a faulty IAC valve so the IAC should be looked at closely. The TPS sensor response can be tested using a real time scan tool. With regard to the other codes, two common denominators across those codes are oxygen sensors and vacuum leaks. To resolve all of these codes, a real time scanner is necessary to look at actual engine operating parameters, for example the response of the oxygen sensors, the integrity of the heater circuit, and, with regard to vacuum leaks, to see if such leaks perhaps show up in measured fuel trims that are read off of a scanner. To have the required diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, the recommended service to get your issue(s) resolved is a check engine light diagnostic. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Knocking noise coming from my passenger side wheel. Went to check but couldn't find anything.

The noise could be due to a worn outer CV joint. This will be particularly likely if the rubber boot (it looks like a bellows) covering the outer CV joint is torn or missing. You can attempt to view the...

Head gasket seeping

A head gasket that leaks or seeps in any way will require the cylinder head to be removed in order to properly fix the leak. In the case of your Chevy Malibu, I would recommend enlisting the assistance of a...

Belts squeaking

Hello, your engine has two belts and adjustable tensioners. The belts should be checked to see if they are dry and cracking, and also to see how stretched they are. The belt's tensioner can be used to tighten the belts...

Related articles

How to Get Lexus Dealership Certified
Lexus dealerships offer automotive technician jobs to those who are Lexus certified through UTI’s Toyota Professional Automotive Technician program.
The Best Used Cars to Buy If You’re a Photographer
If If you are a photographer, and you’re considering buying a used car, the big thing to consider is the type of photography you do. Thanks to the advances in digital photography, chances are you’re not hauling around a lot...
The Best Used Cars to Buy If You Like to Go Off-Roading
Your Your best bet for off-roading is a 4x4 SUV. Depending on the model that pleases you most, though, you might have to shop around a bit to find a good used one. That’s simply because off-roaders typically become very...