Lexus Engine Light Questions And Answers

Welcome to the Lexus engine light Question and Answer Page! This page should save you some time from submitting a duplicate question and having to wait for a response. If you can't find the answers you're looking for here, feel free to submit your own question by using our "Get Help" link, or for immediate solutions, see our Wiring Diagrams page. We will include the model in most questions, so you can use the "Find on this page" function of your browser's "Edit" menu to get relevant info for whatever check engine light concerns you may have. For instance, just type in "ES300" and search for responses relating to this vehicle. You could also type in a Lexus engine light code number by itself such as "P1780" to get all related responses for this trouble code. Just keep hitting "Find next" to go through all relevant check engine light responses. We don't recommend including a model year as this may make your search too narrow, and you may miss out on some relevant posts.

Our Lexus engine light resources cover a very wide range of concerns, but if you can't find what you're looking for through these links or our code listings, then visit the check engine light "Get Help" link on the navigation bar. As always, all repairs should be attempted only by a qualified individual. Please read our Disclaimer before getting started. Thanks for stopping in, and we hope you have found something helpful from our site!

Question:I have a 2000 Lexus ES300. The VSC (Vehicle Stability Control), VSC OFF and Check Engine warning messages came on simultaneously. Also, when I put it in drive, the R is still highlighted and in red. I read on a Lexus forum sight that other people received the check engine light codes PO440, PO441 and PO446 for the VSC problem. I went into Autozone and they gave me a code P1780 (PNP Switch Malfunction), but none of the other three codes came up. Also, they turned it off with their scan tool but the lights all came back on when I started it up to leave the place. My question is what do I do? In the owner's manual, it says it is not serious but take it to the dealer and have them check it out. Can I take it to any auto care shop that deals with foreign vehicles and have them fix the check engine light problem, or should I just unhook the battery for a few seconds and see if it goes away? I don't want to pay alot of money if nothing is really wrong, but I don't want to keep on driving it if there is really an issue. The guy at Autozone checked my tranny fluid and said I needed a full power transmission flush. Is this related to my problem or is it a totally different issue? I don't want the dealer to see me coming and try to make me pay for more than I need to. Thanks for your help.

Answer:Thanks for contacting us with your Lexus engine light concern! The code you are getting is for a Park/Neutral Position Switch concern. The job of this switch is to detect the shifter position and send this information to the computer. If the signal is not received, the computer will default the transmission to the Drive position and trigger the Lexus engine light. The following conditions must be met before this code is set: The computer (ECM) detects that 2 or more circuits are on, the vehicle has been driven for at least 30 seconds at a speed at or greater than 44 MPH and the engine speed must be between 1500 and 2500 RPM. This code is caused by an electrical concern and as such a transmission flush or service will have no effect or benefit. If your fluid is burnt or due for service by mileage it's always a good idea to perform the routine maintenance, but again, it will not fix your Lexus engine light problem. The possible causes of this problem are limited to a short in the PNP switch circuit, a PNP switch malfunction or an internal ECM concern. It's possible and likely that the PNP concern is also causing your VSC light to illuminate as this system also uses info from this sensor. Any competent shop should be able to test this system, but the dealer will likely be your best bet as their technicians are the most highly trained to deal with the Lexus engine light. Either way, the above mentioned faults are the only possible causes so I wouldn't let someone talk you into anything else unless the dealer has a technical service bulletin or parts update to correct this concern. Sometimes manufacturers update parts if a concern is common enough. This is another benefit of having the vehicle serviced by the manufacturer, as this information is often slow to get out to the independent shops. Disconnecting the battery to reset the check engine light is only a temporary fix. The light will likely come back on. Newer computers have built in strategies to turn the check engine light off if a concern is not detected within a certain number of drive cycles. This concern could affect transmission operation and shift feel or timing so I would recommend having it taken care of. It will not likely leave you road side or do any permanent damage so an appointment at your earliest convenience should be fine. Hope this info helps. Let me know if you need any further assistance and have a great day!

Question:I have a 1999 Lexus GS300. I currently have a P1300 Lexus engine light code: Igniter Circuit Malfunction, Bank 1. The car rumbles and sometimes dies. What component is causing this and what most likely is the repair?

Answer:Thanks for submitting your Lexus engine light question. The ECM (computer) uses input signals from pick-up devices (the camshaft position and crankshaft position sensors), to switch the ignition coils primary circuit on and off. The ignition coil is what sends spark to the plugs. The primary ignition circuit is turned off when the ECM delivers a signal to the IGT wire, causing the ignition coil to fire. Side note: an ignition coil fires spark when the current is interrupted and the field is broken, as such this coil fires when the ECM delivers the signal to turn off primary circuit on the IGT wire; make sense? After the computer sends this signal, it then checks to ensure the primary circuit switching has occurred by monitoring the IGF (Ignition Confirmation Signal) circuit. This Lexus engine light code is set when there is no Ignition Confirmation Signal (IGF) received at the ECM (computer) for 2 or more ignition cycles, or when the IGF signal is lost 3 or more times during 6 consecutive IGT signals with the engine running. Possible causes are: open or short circuit in the IGF or IGT circuits (including the coils and wires), faulty ignitor or faulty ECM. You can refer to our automotive circuit testing article for help with testing the wiring. The easiest way to check the ignitor system is to remove the ignition coils and spark plugs, reconnect electrical connectors on the coils, disconnect fuel injectors and install spark plugs in coils and spark plug wires. Ground out the spark plugs on the engine block. Have an assistant crank the engine (5 seconds max) and check for spark at the plugs. Do not come in contact with spark plugs, coils or any related areas as electric shock can occur! Also keep these away from fuel lines and flamable areas. If you have spark on the plug at the coil, but not on the plug on the wire, you may have a faulty wire. Check the resistance of the wire. It should be no more than 25,000 Ohms. If you have no spark on any plug, check wiring and connections on coils and ignitor. Ignitor is located on top of drivers side strut tower. If all wiring tests out okay, you may have a faulty ignitor or coil. You can check ignition coil resistance. With the suspect coil removed, check primary resistance across the terminals. This should be .33 to .52 Ohms cold. Check secondary resistance by measuring from electrical terminal to spark plug terminal. This should be 8,500 - 14,700 Ohms cold. Always have these checks done by a qualified individual, and let us know if you have any further Lexus engine light concerns. Hope this was helpful!

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