Faulty throttle position sensor (internal short or open circuit); Damaged or corroded wiring harness at the TPS connector; Poor ground connection at the TPS or PCM; Failed PCM (rare, but possible if voltage supply is internally shorted); Contamination or wear on the TPS resistive track; Aftermarket accessories tapping into the 5-volt reference circuit

DTC codes / GM codes / P1219

P1219 · GMThrottle Position Sensor Reference Voltage

Q: What does code P1219 mean?

Throttle Position Sensor Reference Voltage. P1219 on GM vehicles indicates that the powertrain control module (PCM) has detected an out-of-range reference voltage on the throttle position sensor (TPS) circuit, typically the 5-volt supply line. The PCM monitors this voltage to determine throttle plate position, and when the signal falls outside the expected range, it sets this code and may limit engine power.

P1219 on GM vehicles indicates that the powertrain control module (PCM) has detected an out-of-range reference voltage on the throttle position sensor (TPS) circuit, typically the 5-volt supply line. The PCM monitors this voltage to determine throttle plate position, and when the signal falls outside the expected range, it sets this code and may limit engine power.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illumination of the check engine light or reduced power message on the dash
Engine may idle erratically or stall when coming to a stop
Hesitation or stumble during acceleration
Transmission may shift harshly or refuse to downshift
Often no symptoms besides the warning light, especially if the fault is intermittent

Common causes, most likely first

Faulty throttle position sensor (internal short or open circuit)
Damaged or corroded wiring harness at the TPS connector
Poor ground connection at the TPS or PCM
Failed PCM (rare, but possible if voltage supply is internally shorted)
Contamination or wear on the TPS resistive track
Aftermarket accessories tapping into the 5-volt reference circuit

How to diagnose and fix it

Use a scan tool to read TPS voltage and check for rationality; compare actual versus commanded throttle position
Inspect the TPS connector and wiring for corrosion, chafing, or loose pins; repair as needed
Measure reference voltage at the TPS connector with the key on, engine off; should be close to 5 volts
Check ground continuity from the TPS to the PCM and chassis ground
Perform a wiggle test on the harness while monitoring TPS voltage to identify intermittent faults
Replace the TPS if voltage supply and ground are good but the sensor signal is erratic or out of range
Clear codes and perform a throttle relearn procedure if required

Don't overlook the 5-volt reference circuit

A common mistake is replacing the TPS when the actual problem is a shorted 5-volt reference wire elsewhere in the harness, which can affect multiple sensors.
The TPS shares its reference voltage with other sensors like the MAP or EGR, so a fault in one can drag down the voltage and set codes in multiple systems.
Intermittent P1219 can be caused by a worn throttle shaft bushing that allows the sensor to move erratically, mimicking an electrical fault.
Aftermarket remote starters or alarm systems that tap into the throttle wiring can introduce noise or voltage drops that trigger this code.
Always check for technical service bulletins (TSBs) for the specific GM model, as some years have known harness routing issues that cause this code.

Can I keep driving with P1219?

You can usually drive with P1219, but expect reduced engine power and possible stalling; avoid aggressive acceleration and have it diagnosed promptly to prevent unsafe driving conditions.

Tools that help

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Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.