P0121

Description
TP SENSOR SYSTEM PERFORMANCE

Throttle Position (TP) sensor measures amount of throttle
opening. PCM uses TP sensor information for fuel delivery
calculations. TP sensor readings during acceleration are much higher
than those during deceleration or idle.
Symptoms

• SES, Service Engine Soon light
• Intermittent stumble on acceleration or deceleration
• Blows black smoke on acceleration
• No start

Causes

• Defective TPS
• Short in the TPS wiring.
• Bad connection at the TPS
• Water or corrosion in connector or sensor

Possible Solutions

• Test the TPS
• Inspect TPS wiring for shorts, corrosion, or damage
• If no TPS signal, check for 5 volt reference at the connector.
• Replace the TPS