P1129Manufacturer-specific code

P1129 Code: Electronic Throttle Control System (Toyota)

On Toyota and Lexus, the P1129 code points to a fault in the electronic throttle control system. The engine goes into limp mode with very little power. On other brands the number means something else.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$0 to $600
Difficulty
Medium
System
Idle and Speed Control
Applies to
Depends on the manufacturer

Common in: Audi, Seat, Toyota, Volkswagen

Updated Reviewed by Renzo Chacca

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What the P1129 code means

P1129 is a manufacturer-specific code: the 1 in the second position means each automaker defines what it stands for, not the generic standard. That is why the same number means different things depending on the vehicle, as the table below shows. This page covers the Toyota and Lexus meaning.

ManufacturerMeaning of P1129
Toyota and LexusElectronic throttle control system
Volkswagen, Audi, Seat and SkodaLong term fuel trim, multiplicative, bank 1: system too rich

Toyotas with an electronic throttle (ETCS-i) move the throttle plate with an electric motor controlled by the computer, which reads the pedal with two sensors. When it detects a fault, it goes into limp mode: a spring holds the throttle plate almost closed and the engine barely accelerates.

The computer sets the P1129 code when the throttle system as a whole does not respond the way the computer expects.

Before you repair anything, confirm the make, model, year and engine. With manufacturer codes, the same number can change even between engines from the same brand.

P1129 code symptoms

  • Check engine light on.
  • Limp mode: the engine barely accelerates.
  • High or unstable idle.
  • The engine may stall.

Likely causes of the P1129 code

  1. Dirty or failed throttle body. Confirm it with the tests in the diagnosis section.
  2. Connectors. Check the locking tab and the pins, and look for moisture or corrosion.
  3. Low battery voltage. Confirm it with the tests in the diagnosis section.
  4. Pedal. Confirm it with the tests in the diagnosis section.

How to diagnose the P1129 code step by step

  1. Read all stored codes and the live data for the pedal and the throttle plate.
  2. Clean the throttle body with the ignition off.
  3. Check the connectors at the throttle body and at the pedal.
  4. Check the battery and the grounds.
  5. Perform the idle relearn if the manufacturer calls for it.

How to fix the P1129 code

  • Clean or replace the throttle body.
  • Replace the pedal if its sensors fail.
  • Repair the connectors or the wiring.
  • Clear the codes, confirm that the P1129 code does not come back, and verify the repair on a test drive.

Technical reference data

  • Throttle motor: approximate resistance of 0.3 to 100 ohms depending on the model; check the service manual.
  • Pedal: two signals, VPA and VPA2, that must move in parallel.
  • P1xxx codes are manufacturer-specific: confirm the definition with a scan tool that supports your brand.
  • Values are approximate: check the manufacturer data for your vehicle.

Brand-specific notes

Common on Corolla, Camry, RAV4 and Tacoma models from the 2000s.

If your vehicle is another brand, check the table above for the meaning its manufacturer gives the code, and confirm it with a scan tool that supports that brand.

Frequently asked questions about P1129

What does the P1129 code mean on a Toyota?
It points to the electronic throttle control system. The engine goes into limp mode with very little power.
Does P1129 mean the same thing on every brand?
No. On Volkswagen it stands for the long term fuel trim, multiplicative, bank 1: system too rich.
Can I drive with a P1129 code?
Only with great caution. Power is minimal, and that can be dangerous on fast roads or when merging. Drive straight to a shop at low speed if you must move the vehicle.
How much does it cost to fix P1129?
On a Toyota the cost runs from about $0 to $600. A cleaning or a battery fix costs little, while a throttle body or pedal replacement costs more.
Will a P1129 code clear itself?
If it was caused by a momentary low battery voltage, limp mode may end after a restart. A dirty or failing throttle body will bring the code back.
What is the most common cause of P1129?
A dirty or failed throttle body. Low battery voltage, bad connectors and the pedal sensors are the other things to check.

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