Throttle Position Sensor Output Circuit Low
The P2621 code indicates that the throttle position sensor (TPS) output circuit voltage is lower than expected. The TPS is a potentiometer that sends a voltage signal to the engine control module (ECM) indicating throttle plate angle. A low voltage reading suggests a short to ground, a faulty sensor, or wiring issues. This can cause incorrect air-fuel mixture, leading to poor engine performance.
01. Most Common Causes
- Faulty throttle position sensor
- Short to ground in TPS signal circuit
- Damaged wiring or connectors
- Corroded terminals
- ECM failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor acceleration or hesitation
- Rough idle or stalling
- Reduced fuel economy
- Engine may enter limp mode
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect TPS wiring and connector for damage or corrosion.
Step 3: Measure TPS signal voltage at idle (should be ~0.5-1.0V) and wide open throttle (~4.5V).
Step 4: Check for short to ground by disconnecting TPS and measuring resistance between signal wire and ground.
Step 5: If sensor voltage is low and wiring is good, replace TPS.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the vehicle may experience poor performance, stalling, or enter limp mode, which can be unsafe.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY replacement of the throttle position sensor, including parts. Professional labor may add $50-$100.