Skip the auto shop - Our mechanics make house calls

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?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: P0301

Diagnostic Trouble Code P0301 means that Cylinder No. 1 is misfiring but the causes of that can be very varied. The fuel injector could simply be dead or there is little cylinder compression due to a burned valve or leaky...

Q: vanos solenoid bmw

The nature of the repair will have to do with the faults stored in the DME (engine computer). Spark plugs, though rated at 100K miles, have a service life of about 60K miles and should be replaced at tht mileage....

Q: I have a95 Chrysler Sebring with a 2.5liter v6 it starts fine runs 15 min then chokes an pukes for 15 min then comes out of it run

Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both. Spark related problems generally will result from things like ignition coils, crankshaft...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.