CEL Code P1121...help - Lexus IS Forum
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post #1 of 11 (permalink) Old 01-23-2009, 11:27 PM Thread Starter
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CEL Code P1121...help

I got a code of P1121 accelerator pedal position sensor. My car will start but I have to press on the pedal about 3/4 down inorder to go forwars and it will only go 25 mph or will speed up all of a sudden. My husband says we have to replace the APPS but I can't find the part. Has anyone had this problem and can anyone help me?
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post #2 of 11 (permalink) Old 01-26-2009, 01:46 PM
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Are you sure you do not have PO121 DTC code?

I do not see a PO1121? The closest Lexus code to this is PO1126.

You also do not list the year of your vehicle, it can make a difference in some cases. Also is it an automatic or manual, as there is some trouble codes for the clutch motor communicating with the TPS - they work together in manual trans. systems.
I have never heard of an APPS (accelerator pedal position sensor maybe?), but remember our vehicles have a manual/ electronic combined system.

Here is the details of the codes





If it is a TPS there not that expensive - Throttle Position Sensor 8945230150 $83.88

This sensor can be tested by a shop to check the output/ input before replacing uneccessarily.

Thats all I have, but something to build on.

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post #3 of 11 (permalink) Old 01-27-2009, 04:57 PM
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P1121: accelerator pedal position sensor range/performance problem. That means the VPA & VPA2 readings are out of wack and the accelerator pedal position sensor is no good (internal short/failure).

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Last edited by Gray Rider; 01-28-2009 at 08:37 AM.
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post #4 of 11 (permalink) Old 01-28-2009, 08:22 AM
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digger08, there is no 0 after the P. So it's P1121 not p01121.

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post #5 of 11 (permalink) Old 01-28-2009, 08:29 AM
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Here are the Lexus controlled codes:

P1120 > Accelerator pedal position sensor circuit malfunction.

P1121 > Accelerator pedal position sensor range/performance problem.

P1125 > Throttle control motor circuit malfunction.

P1126 > Magnetic clutch circuit malfunction.

P1127 > ETCS actuator power source circuit malfunction.

P1128 > Throttle control motor lock malfunction.

P1129 > Electronic throttle control system malfunction.

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post #6 of 11 (permalink) Old 01-28-2009, 03:28 PM
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Quote:
Originally Posted by Gray Rider View Post
digger08, there is no 0 after the P. So it's P1121 not p01121.
My bad. I got to read things more closely!

Digger08
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post #7 of 11 (permalink) Old 09-19-2013, 04:16 PM
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How was this problem fixed? I have the same code and I don't want to buy a 300 dollar sensor and have it be something else
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post #8 of 11 (permalink) Old 09-19-2013, 04:59 PM
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If you grab the diagnostic manual, there should be a procedure to test these parts first.
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post #9 of 11 (permalink) Old 07-16-2016, 06:00 PM
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I had an error code 1121 on my 2001 IS300. TRAC OFF light was flashing and car went into limp mode. Thanks to the threading ClubLexus forums, I took my car into Longo Lexus and told them about the Toyota Economic Loss Settlement. They checked and said that my vehicle was eligible. They gave me a loaner and replaced the whole throttle body assembly at no charge. Service was great and car is running perfectly. But hurry because I think the coverage ends in August 2016. Thanks to the thread and Julien at Longo.
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post #10 of 11 (permalink) Old 09-14-2016, 11:37 AM
 
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Quote:
Originally Posted by hanooo View Post
I had an error code 1121 on my 2001 IS300. TRAC OFF light was flashing and car went into limp mode. Thanks to the threading ClubLexus forums, I took my car into Longo Lexus and told them about the Toyota Economic Loss Settlement. They checked and said that my vehicle was eligible. They gave me a loaner and replaced the whole throttle body assembly at no charge. Service was great and car is running perfectly. But hurry because I think the coverage ends in August 2016. Thanks to the thread and Julien at Longo.
Hanooo, the whole throttle body is very expensive and it's cover? That's is so nice to hear that Toyota took care of your problem. I have the same year and identical problem. Can you tell me what's other parts is being listed in your invoice?
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post #11 of 11 (permalink) Old 03-07-2017, 10:59 PM
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My 01 is300 did the exact same thing. On this board and clublexus someone posted a fix to remove the accelerator pedal position sensor from the throttle body and cut away part of the cover over the connector solder joints and re-solder them. He posted a detailed explanation and a pic which I subsequently have not been able to return to. As a last resort I tried this as I was already planning to buy a new sensor so if I messed it up it didn't really matter. Well I must say the fix worked perfectly and it only cost me a couple hours time! Whoever figured that re-solder thing out is pure genius! I consider myself a fairly smart guy and I never would have guessed that particular problem.

The only thing I disagree with, and I've seen it a couple times on this board, is how the APPS works. It's a point of technicality but I spent 25 years repairing electronic and computer systems so it bugs me. The APPS on the 01 is300 has two potentiometers but they are not inverse they are different value ranges of resistance. The point of which is not safety but to develop a reliable difference of potential. In regular electrical systems difference of potential (voltage) is measured to ground (earth to be exact). On vehicle and other "floating ground" electrical systems "ground" isn't measured to earth (therefore not truly ground but the negative potential hence the - ) it is simply the direction of electron flow and the potential can vary. The purpose of having two pots of differing values is to create a voltage "divider" in which the difference of potential remains fairly constant (close enough taking into account physics) through a range regardless of fluctuating potential either negative or positive applied to the system. Otherwise in this system, because vehicle voltage is not super reliable, slight changes in input voltage would be interpreted as changes in pedal position.

Just my two cents worth with a couple extra thrown in!

P.S. the sensor will test good with ohmmeter, you'll just have to try the fix to know if that is the problem.

Last edited by HeyTimborino; 03-07-2017 at 11:05 PM. Reason: Added tip
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