What Does P1126 Mean?
P1126 indicates the Throttle Position (TP) sensor circuit is intermittently producing a voltage above the expected range. The ECM detects sporadic voltage spikes from the TPS, which it interprets as sudden throttle opening events. This can cause unwanted fuel enrichment, transmission downshifts, and erratic idle behavior. The intermittent nature distinguishes this from a steady high-voltage fault and typically points to a wiring or connector issue.
Safety Warning
Intermittent high TPS voltage can cause unexpected surges in engine power and unwanted transmission downshifts, which can be dangerous during normal driving. The ECM may also enter failsafe mode at unpredictable times.
Common Causes
28%
TPS signal wire intermittently shorting to the 5V reference circuit
25%
TPS sensor with intermittent internal fault producing voltage spikes
22%
Loose TPS connector allowing contact bounce and false high readings
15%
Damaged TPS wiring harness near throttle body (heat damage from exhaust proximity)
10%
EMI interference on the TPS signal wire from aftermarket electronics
Diagnostic Steps
1
Step 1: Monitor TPS voltage at idle over several minutes. The voltage should remain stable at the closed-throttle value. Any sudden spikes above the expected idle voltage confirm the intermittent high-voltage condition.
2
Step 2: Wiggle the TPS connector and signal wire while monitoring voltage. Spikes coinciding with connector movement confirm a connection issue.
3
Step 3: Inspect the TPS wiring harness for heat damage, chafing, or contact with the throttle body or exhaust components. Pay special attention to the 5V reference wire — a chafe between the signal and reference wires would cause intermittent high readings.
4
Step 4: Disconnect the TPS and measure the sensor resistance through its full range of motion using an ohmmeter. Look for sudden resistance drops that would cause voltage spikes.
5
Step 5: Replace the TPS if internal faults are found. Ensure proper connector seating and apply dielectric grease. Clear codes and road test to verify the intermittent condition is resolved.
Estimated Repair Cost
$50 - $400
Parts + labor, varies by vehicle and location
P1126 indicates the Throttle Position (TP) sensor circuit is intermittently producing a voltage above the expected range. The ECM detects sporadic voltage spikes from the TPS, which it interprets as sudden throttle opening events. This can cause unwanted fuel enrichment, transmission downshifts, and...
The most common cause of P1126 (Throttle Position (TP) Sensor Circuit Intermittent High Voltage) is: TPS signal wire intermittently shorting to the 5V reference circuit
Typical repair costs for P1126 range from $50 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent high TPS voltage can cause unexpected surges in engine power and unwanted transmission downshifts, which can be dangerous during normal driving. The ECM may also enter failsafe mode at unpredictable times.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1126 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Throttle Control
Difficulty
Type
Manufacturer
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