P0122
Throttle Position Sensor (TPS) Circuit Low Input
When a vehicle powertrain module registers the fault code P0122, it points directly to an internal system malfunction identified as "Throttle Position Sensor (TPS) Circuit Low Input". Operating your engine under this condition may degrade long-term fuel maps.
Driver's Summary
Storing code P0122 is your car's way of telling you something is wrong with the throttle position sensor (tps) circuit low input. Drivers typically experience dead spots in throttle, low power, hesitation when this code is active. The vehicle is usually drivable, but the root cause needs attention soon to avoid more expensive repairs down the road.
Symptoms
Dead spots in throttle, low power, hesitation
Common Causes
- Short to ground in TPS wiring
- Defective TPS sensor
- Loose sensor mounting
- Faulty PCM
How to Fix
- 1 Replace TPS sensor
- 2 Test sensor ground
- 3 Secure sensor mounting
- 4 Inspect throttle linkage
Technical Explanation
Detection of P0122 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. Sensor output is cross-validated against complementary sensor data (such as MAF vs. MAP correlation, or upstream vs. downstream O2 comparison) to confirm the fault is genuine and not a result of a sensor reading an actual engine condition. The MIL illuminates after the fault is confirmed on two consecutive drive cycles, and the freeze frame data captured at first detection is stored in the PCM's memory for diagnostic reference.
Is It Safe to Drive?
Code P0122 allows for cautious short-distance driving, but the underlying cause — most likely short to ground in tps wiring — will worsen with time. Fuel economy suffers, and ignoring the fault for weeks can turn a $80 fix into a much larger repair bill.
Mechanic's Pro Tip
Module replacement should always be the last resort for P0122 after exhaustively verifying all power supply circuits, ground connections, and communication bus wiring. Use a wiring diagram to locate all fuses, relays, and ground points for the affected module, and measure voltage drop on each ground with the circuit loaded. A module "failure" is frequently a corroded ground eyelet or a weak battery causing brownout conditions — fix these first and you'll save hundreds of dollars on an unnecessary module replacement.
TPS sensor: $50 - $120; Labor: $80