What Does P2621 Mean?
The PCM has detected abnormally low voltage in the throttle position output circuit. This indicates a short to ground or excessive resistance in the throttle control system output.
Safety Warning
Vehicle will likely enter reduced power mode with limited acceleration. Unsafe for highway driving or situations requiring normal power.
Common Causes
35%
Wiring shorted to ground in throttle position output circuit
30%
Failed throttle body actuator motor with internal short
20%
Water intrusion or corrosion causing short in throttle body connector
15%
PCM internal fault with output driver short to ground
Diagnostic Steps
1
Step 1: Disconnect throttle body connector and measure resistance to ground on control circuits (should be high resistance, >10k ohms)
2
Step 2: Inspect wiring harness for damage, particularly where it routes near sharp edges or heat sources
3
Step 3: Check throttle motor resistance and compare to specifications (reject if shorted or out of range)
4
Step 4: Monitor live throttle output voltage at PCM connector with throttle body disconnected
5
Step 5: Test for PCM fault by checking output signal integrity with oscilloscope
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The PCM has detected abnormally low voltage in the throttle position output circuit. This indicates a short to ground or excessive resistance in the throttle control system output.
The most common cause of P2621 (Throttle Position Output Circuit Low) is: Wiring shorted to ground in throttle position output circuit
Typical repair costs for P2621 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle will likely enter reduced power mode with limited acceleration. Unsafe for highway driving or situations requiring normal power.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2621 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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