Code Definition

P1220 — Timer control circuit malfunction

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

About P1220

P1220 is a manufacturer-specific powertrain diagnostic trouble code recorded for Toyota 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 an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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

On Toyota diesel engines fitted with an electronically controlled rotary distributor injection pump, injection timing is varied by a timing control valve, often abbreviated to TCV, mounted on the pump body. The engine ECU pulse width modulates that valve to regulate internal pump pressure, which moves the timer piston and advances or retards the point at which injection begins relative to crankshaft position. The ECU then confirms actual timing using the pump speed sensor or the timing signal fed back from the pump and compares it against the commanded value. DTC P1220 is set when the ECU dete...

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