Q: Car idles and multiple trouble codes are triggered

asked by on

My Lexus only idles when it's not moving and car is on. I had put in New spark plugs on the left side of the motor. But car still idles. The codes I get are p0301,p0300,p0303,p0172,p0139 and C1201. I have not found and vacuum leaks and all plugs are connected. I can't figure what the problem is?

My car has 143325 miles.
My car has an automatic transmission.

Hi there. If this vehicle is having an idle concern, I have to ask if you may be having a stumble or stall issue when coming to a stop.

If so, your vehicle may be covered under a special service campaign for engine misfire due to excessive carbon buildup in the quench zone of the combustion chamber. However, all of the spark plugs need to have been replaced and with the correct type, iridium, before they will even consider it; thus relieving the misfire codes.

As for the later 3 codes stored, these could be related to the fuel pressure sensor on the high pressure fuel rails and should be inspected by a qualified technician as this system could have upwards of 1500psi of fuel pressure in the rails.

The pressure sensor has 3 wires, one of which is blue and is the VC (vehicle communication) wire that carries the 5 volt reference. If this signal goes open, it can set the additional codes or a combination of them. If this circuit becomes shorted, then communication shuts down and the vehicle usually will not start.

YourMechanic has several available technicians that can assist you with a Check Engine Light inspection and can perform a spark plug replacement, or any other repairs that are needed.

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
  1. Home
  2. Questions
  3. Car idles and multiple trouble codes are triggered

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

Q: Car runs rough below 40 MPH

The code P0171 means that the engine running lean, which typically stems from a few possible sources: a faulty mass air flow sensor, or clogged intake manifold gaskets or fuel filter. The codes P0301 and P0316 can mean that cylinder...

Q: Q: Car is shaking violently

Since you have listed a number of issues, there is no certain way to provide you with a definitive answer. It's highly unlikely that all your issues are rooted in one part or system. If the plugs are covered in...

Q: Push gas in gear and it boggs down a lot

It sounds like you may have an over fueling situation going on where the motor is being provided more fuel than it can efficiently burn, resulting in the raw fuel smell you describe. This can happen for many different reasons...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.