Throttle Position Output Circuit Low
The P2621 code means the vehicle's onboard diagnostic system has detected: Throttle Position Output Circuit Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $100 - $700 (parts and labor)
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Common Symptoms
- Transmission upshifts too early
- Traction control overactive
- Poor acceleration response
- Cruise control disengages
Probable Causes (Ranked by Likelihood)
- Short to ground in throttle output wiring Very High
- Receiving module pulling signal low High
- ECM output driver shorted low Moderate
- Corroded output circuit connector Low
Frequently Asked Questions
Why does my car shift too early with P2621?
The low signal makes the transmission module think the throttle is barely open, so it upshifts early for fuel economy. The module does not know the driver is actually demanding acceleration.
Can P2621 cause sluggish acceleration?
Indirectly, yes. The transmission shifts too early for the driving conditions, making the vehicle feel sluggish even though the engine itself may be producing normal power.
How do I test the throttle output circuit?
Use a scan tool to read throttle position at the ECM, then check the output signal at the receiving module connector. They should match proportionally.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Check throttle output circuit for short to ground
-
Compare ECM throttle input to output signal
-
Disconnect receiving modules to isolate short
-
Inspect connectors for corrosion
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- 2010-2020 Toyota RAV4
- 2012-2019 Honda Accord
- 2008-2018 Ford Escape
- 2011-2020 Chevrolet Equinox
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