Code Definition

P1220 — Throttle Position Sensor circuit fault

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: GM

About P1220

P1220 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1220 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1220 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The throttle position sensor tells the Engine Control Module (ECM) how far the throttle plate is open, and on an electronic throttle system it is a dual track device with two independent signal outputs so the module can cross check one against the other before it trusts either. Each track is supplied with a 5V reference and a low reference, and each returns a signal voltage proportional to throttle angle, typically sweeping from around 0.5V at closed throttle to around 4.5V at wide open throttle. DTC P1220 is set when the ECM detects a fault in the throttle position sensor signal circuit, whic...

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