OBD-II Code C1750: Accelerator Position Sensor Out of Range

What Does C1750 Mean?

Code C1750 indicates the vehicle's control module receives an erratic or illogical voltage signal from the accelerator pedal position (APP) sensor. This sensor dictates throttle response based on pedal depth. When the signal falls outside the manufacturer's programmed parameters, the computer restricts engine power to prevent unintended acceleration.

Technical definition: The SAE/OBD-II definition for C1750 is 'Accelerator Position Sensor Out of Range'. The APP sensor uses dual potentiometers for redundancy. This code triggers when the primary and secondary voltage signals fail to correlate or drop below/exceed the expected 0.5V to 4.5V operating range.

Can I Drive With C1750?

⚠️Yes, But With Caution. You can drive short distances, but the vehicle often experiences unpredictable acceleration or locks into a low-power 'limp mode' capped at 30-50 mph. Drive directly to a safe location or repair shop to avoid stalling in traffic. Extended driving in limp mode forces an incorrect air-fuel mixture, risking an $800-$2500 catalytic converter replacement.

Common Causes

• Faulty Accelerator Pedal Position (APP) Sensor (Very Common) — The sensor's internal potentiometers wear out over thousands of pedal presses, sending erratic voltage spikes or dead spots to the computer.
• Wiring or Connector Issues (Common) — Damaged wires or corroded connector pins create high electrical resistance, distorting the sensor's signal. This frequently occurs due to moisture tracked in on driver footwear.
• Low Battery Voltage or Charging System Failure (Common On Some Makes) — A weak battery or failing alternator drops the 5V reference signal required by the sensor. On Mitsubishi models, C1750 specifically flags this system voltage drop rather than a pedal fault.
• Dirty or Sticking Throttle Body (Less Common) — Carbon buildup causes erratic idling that the computer misinterprets as a pedal fault. This is a documented secondary trigger on 2007-2015 Ford Focus models.
• Physical Obstruction of Pedal (Rare) — Bunched-up aftermarket floor mats block full pedal travel, preventing the sensor from reaching its programmed maximum voltage.
• Faulty TPMS Control Unit (Rare) — On specific Nissan and Infiniti models, a failed Tire Pressure Monitoring System (TPMS) module corrupts CAN bus data, logging a false C1750 code.

Symptoms

• Engine Stuck in 'Limp Mode' — The computer restricts speed to 30-50 mph and limits RPMs to prevent unintended acceleration.
• Poor, Erratic, or Delayed Acceleration — The vehicle hesitates, surges, or ignores gas pedal input entirely.
• Check Engine and Traction Control Lights On — The dashboard illuminates warning lights because the ABS and Traction systems disable themselves when pedal input is untrustworthy.
• Erratic Engine Idle — The engine revs up or idles unstably without driver input.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Replace Accelerator Pedal Position (APP) Sensor Assembly — Parts: $75-$200, Labor: $80-$150, ~1.0 hr book time (Intermediate)
  Ford Focus (2012-2015): OEM BV6Z-9F836-C (Alt: Standard Motor Products APS338)
  Dodge Ram 1500 (2003-2006): OEM 53032753AC (Alt: Dorman 699-199)
• Clean APP Sensor Connector — Parts: $10-$15, Labor: $0-$50, ~0.5 hr book time (DIY)
• Replace Faulty Battery — Parts: $150-$250, Labor: $25-$50, ~0.5 hr book time (DIY)
• Perform Pedal Relearn Procedure — Parts: $0, Labor: $50-$120, ~0.5 hr book time (Professional)
• Repair Damaged Wiring or Grounds — Parts: $10-$30, Labor: $120-$300, ~2.0 hr book time (Professional)

Used vs. New Parts: Buying Guide

When a used part is worth it: Buying a used pedal assembly makes sense for vehicles over 15 years old where a new OEM part exceeds $300.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Verify the exact part number match.
• Inspect the connector pins for green corrosion or bent metal.
• Ensure the pedal spring returns smoothly without binding.

Decision logic:

• If The vehicle is less than 10 years old and a new part costs under $150 → Buy a new OEM part for the warranty and guaranteed lifespan.
• If The OEM part is discontinued or costs over $300 → Purchase a used part from a low-mileage donor vehicle.

Warranty tradeoff: Used parts carry a 30-day warranty covering only the part. New OEM parts carry a 1-2 year warranty.

Worst-case if a used part fails: $300 if a used part fails, requiring you to pay for a second replacement and additional labor.

What Happens If You Wait — Timeline

1. 0-1 month: Intermittent hesitation. Check Engine Light toggles on and off. The car occasionally enters limp mode but resets after restarting the engine. (MPG impact: 0-5%% · Added cost: $0)
2. 1-4 months: Hesitation becomes frequent. The Check Engine Light stays on permanently. Limp mode engages daily, making highway driving unsafe. (MPG impact: 5-15%% · Added cost: $50-$150 in wasted fuel and potential towing costs.)
3. 4+ months: Sustained driving with an incorrect air-fuel mixture overheats and destroys the catalytic converter. The vehicle is undrivable. (MPG impact: 25%+% · Added cost: $800-$2500 for catalytic converter replacement.)

Cost of Not Fixing It

• Immediate: Unpredictable acceleration and sudden limp mode engagement creates a severe safety hazard in highway traffic. (Added cost: $100-$250 for emergency towing.)
• 3+ months: Sustained driving with erratic throttle inputs forces an incorrect air-fuel mixture, overheating and destroying the catalytic converter. (Added cost: $800-$2500 for catalytic converter replacement.)

Diagnosis Steps

1. Read Codes and Live Data
   Use an OBD-II scanner to view live data for the Accelerator Pedal Position sensors (APP1, APP2). As you press the pedal, both must show a smooth, linear voltage increase. Expect ~0.5V at idle rising to ~4.5V at full throttle. Any dropouts confirm a bad sensor.
   Tools: OBD-II Scanner with Live Data (Beginner)
2. Check Technical Service Bulletins (TSBs)
   Search NHTSA.gov for TSBs related to your specific year/make/model and C1750. Manufacturers frequently issue software updates or extended warranties for known pedal sensor defects.
   Tools: Internet Access (Beginner)
3. Visually Inspect the Pedal Area
   Verify no floor mats, debris, or aftermarket pedal covers are blocking the accelerator's full range of motion.
   Tools: Flashlight (Beginner)
4. Inspect the Wiring and Connector
   Unplug the pedal sensor connector. Look for green corrosion, bent pins, or moisture. Spray both ends thoroughly with electrical contact cleaner, let dry, and reconnect.
   Tools: Flashlight, Electrical Contact Cleaner (Beginner)
5. Check Battery and Charging System
   Test the battery voltage with the engine off (12.6V) and running (13.7-14.7V). Low voltage causes the PCM to drop the 5V reference signal to the pedal sensor.
   Tools: Multimeter (Intermediate)
6. [PRO TIP] Test APP Sensor Correlation
   APP sensors use two signals. APP1 voltage is typically double APP2 voltage (e.g., APP1 is 0.8V-4.5V, APP2 is 0.4V-2.25V). Graph both signals on a scanner. If one signal is noisy or fails to track proportionally with the other, replace the pedal assembly.
   Tools: Advanced Scan Tool or Oscilloscope (Advanced)
7. Check Chassis Ground Points
   Locate the main ground points for the engine and chassis using a service manual. Remove the bolts, wire brush the metal contacts until shiny, and reinstall to ensure a stable sensor reference voltage.
   Tools: Socket Set, Wire Brush, Service Manual (Intermediate)

When This Code Triggers (Freeze-Frame Conditions)

• Engine Load: 20-50% (The code frequently logs under partial load conditions where the pedal is held steady or moved slowly.)
• Vehicle Speed: 25-60 mph (Triggers during city or highway cruise conditions when voltage fluctuations from a failing sensor become apparent.)

Related Codes

• P2138 — Indicates a voltage correlation error between the two internal APP sensors. If P2138 and C1750 appear together, the pedal assembly requires replacement.
• P193B — A throttle signal code common on Ford vehicles. If present with C1750, clean the electronic throttle body before replacing the pedal.
• P2121 — The generic Powertrain equivalent of C1750. P2121 is set by the engine computer, while C1750 is set by the ABS/Traction module.

Climate & Environmental Factors

• Wet Footwear and Humidity: Snow or rain tracked into the driver's footwell evaporates and forces moisture into the APP sensor connector, corroding the pins and triggering the code.
• Road Salt: Corrosive salt spray destroys chassis ground straps. A corroded ground alters the sensor's reference voltage, causing the computer to read a false out-of-range signal.

How to Talk to a Mechanic About This Code

Say this: "I have a C1750 code and the car is hesitating. Please check the live data from the accelerator pedal sensors (APP1 and APP2) to confirm their operation before recommending a part replacement."

This directs the technician to test the component rather than blindly replacing parts, saving you money if the issue is just a dirty connector.

Avoid saying:

• 'My gas pedal is acting weird, just fix it.'
• 'Just replace the accelerator sensor.'

Questions to ask before authorizing the repair:

• Did the live data show voltage dropouts or a correlation error?
• Did you inspect the sensor's electrical connector for corrosion first?
• Does my vehicle require a computerized pedal relearn procedure after installation?

Where to Take It: Dealer vs Independent vs Chain

• Dealer:
  Best for: Vehicles under warranty, Known manufacturer quirks (Mitsubishi battery issues, Nissan TPMS faults), When a software update is the required fix
  Downsides: Labor rates are 50% higher than independent shops., Dealers default to replacing entire assemblies rather than repairing wiring. (Typical cost: +50% vs. baseline)
• Independent Shop: Best fit for most out-of-warranty repairs. Ensure they have a bidirectional scanner capable of performing the pedal relearn procedure.
  Best for: Out-of-warranty vehicles with straightforward diagnosis (e.g., P2138 is also present), Drivers seeking better pricing on parts and labor
  Downsides: May lack expensive dealer-level tools for specific software calibrations. (Typical cost: +0% vs. baseline)
• Chain Shop: Avoid for initial diagnosis. Acceptable only if you are certain the pedal assembly requires replacement.
  Best for: Simple part replacements when you have already diagnosed the issue.
  Downsides: Technicians lack in-depth diagnostic experience for complex electrical faults. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the total estimated repair cost exceeds 50% of your car's current private-party value, consider selling the vehicle.

• Car worth $3500, fix is $250: Fix it. The cost is well below the threshold.
• Car worth $4000, fix is $2100: Walk away. A $2100 quote indicates severe wiring harness or PCM damage exceeding 50% of the car's value.

What Scan Tool You Need for This Code

Minimum: An OBD-II reader capable of displaying live data streams (PIDs).

A $20 code reader cannot display live voltage data from the APP sensors. Without live data, you cannot verify if the sensor has dead spots or if the wiring is at fault.

Budget: BlueDriver Pro (~$100) — Connects to your smartphone to view and graph live voltage data for the accelerator pedal sensors.

Mid-range: Foxwell NT510 Elite (~$180) — Provides live data and performs the critical 'Accelerator Pedal Relearn' procedure required after replacing the sensor.

Professional: Autel MaxiSYS MS906 (~$1000) — Offers full bidirectional control, advanced ECU coding, and OEM-level diagnostics for complex wiring faults.

Rent vs buy: Buy the midrange pick. Free rental scanners from auto parts stores rarely support the pedal relearn procedure required to complete this repair.

How to Clear the Code After You Fix It

1. Reconnect the battery if disconnected.
2. Use an OBD-II scan tool to clear the diagnostic trouble codes.
3. Perform a pedal relearn procedure using a bidirectional scanner.
4. Complete a 20-minute drive cycle to verify the code does not return.

Drive cycle (~20 minutes): Start the engine cold and idle for 3 minutes. Drive 15 minutes in mixed city/highway conditions, ensuring several smooth acceleration and deceleration events from 0 to 55 mph.

Readiness monitors affected: Comprehensive Component Monitor (CCM)

Before emissions retest: drive at least 50 miles to fully set monitors.

Watch out for:

• Failing to perform the pedal relearn procedure causes the code to return immediately upon startup.
• Clearing the code resets emissions monitors to 'incomplete', resulting in an automatic smog test failure.

Will This Fail Emissions / State Inspection?

Yes — this code typically fails an OBD-II emissions inspection.

• California: An illuminated Check Engine Light is an automatic failure. Clearing the code resets readiness monitors, requiring a 50-mile drive cycle before retesting.
• Texas: Active codes fail the OBD-II test. The Check Engine Light bulb must also illuminate during the key-on-engine-off check.

Most Commonly Affected Vehicles

• Ford Focus (2007-2015) — Check TSBs 15-0121 and 16-0129. A dirty electronic throttle body frequently causes secondary pedal codes on these models.
• Dodge Ram 1500/2500 (2003-2006) — Notorious for electronic throttle control failures. Replacing the entire pedal assembly is the standard fix.
• Mitsubishi Outlander, Lancer (2008-2018) — C1750 indicates 'Voltage Out of Range' for the Adaptive Cruise Control ECU. Always test the battery and alternator first.
• Nissan/Infiniti Altima, M35, FX (2007-2015) — C1750 triggers alongside C1751/C1752 due to a data error from a failed Tire Pressure Monitoring System (TPMS) module.
• Toyota Corolla, Prius (2005-2014) — The similar code P1750 indicates a 'Brake ECU Malfunction' traced to wheel speed sensors, not the gas pedal.

Manufacturer-Specific Notes

• Mitsubishi: C1750 points to a system voltage drop affecting the Forward Collision Mitigation computer, not the pedal sensor. Diagnose the battery and alternator first.
• Ford: Ford Focus models frequently log C1750 due to wiring harness chafing or a dirty throttle body rather than a failed pedal sensor.
• Nissan/Infiniti: A failed TPMS module disrupts the CAN bus network, causing the computer to log a false C1750 pedal code.
• General Motors: GM issued Special Coverage Adjustment N192221390 for related pedal codes on 2016-2018 models, extending the APP sensor warranty to 10 years/150,000 miles.

Real Owner Stories

Ford Focus with intermittent acceleration loss

Owner experienced random loss of acceleration over three months. Code C1750 finally triggered.

What they tried:

1. Ignored the issue initially.
2. Scanned the code using a FORScan tool.

Outcome: The owner removed the accelerator pedal, disconnected the sensor, and cleaned the connector pins with electrical contact spray. The code cleared and did not return, proving a dirty connection mimics a failed sensor.

Lesson: Always clean the electrical connector before buying a $150 replacement sensor. Contact cleaner is a $10 diagnostic tool that fixes 30% of these cases.

Mitsubishi Outlander with a dead battery

After jump-starting a dead battery, the check engine light illuminated with code C1750.

What they tried:

1. Charged the battery and cleared the code.

Outcome: On Mitsubishi models, C1750 means 'Voltage Out of Range' for an ECU, not a pedal fault. The root cause was a parasitic drain from a failed Bluetooth module killing the battery.

Lesson: Code definitions vary by manufacturer. For Mitsubishi, C1750 requires a full battery and alternator test before inspecting the gas pedal.

How to Prevent This Code From Triggering

• Clean electrical connectors and apply dielectric grease (Every 3 years or when working in the footwell) — Moisture from wet shoes corrodes the pedal connector pins. Dielectric grease seals out water and prevents the high resistance that triggers C1750.
• Secure floor mats on factory retention hooks (After every car wash or interior cleaning) — Sliding floor mats physically block the pedal's travel, forcing the sensor to report an out-of-range value.
• Test battery and alternator health (Annually before winter) — Sensors require a stable 5V reference voltage. A weak battery causes voltage fluctuations that trigger false sensor codes.

Frequently Asked Questions

Can I fix code C1750 myself?

Yes, if the issue is a dirty connector, floor mat obstruction, or simple sensor swap. The accelerator pedal assembly is easily accessible in the driver's footwell. Stop DIY and visit a shop if the repair requires complex wiring fixes or a computerized pedal relearn.

How much does it cost to fix C1750?

Professional diagnosis and replacement of the accelerator pedal assembly costs between $150 and $350. DIY sensor replacement costs $75 to $200 for the part alone. Cleaning a dirty connector or removing a floor mat costs nothing.

Will clearing the code fix the problem?

No. Clearing the code temporarily turns off the warning light, but it returns immediately once the computer detects the out-of-range voltage again. You must repair the underlying electrical or mechanical fault.

What are the most common misdiagnosis mistakes for C1750?

The biggest mistake is replacing the pedal sensor without checking live data or inspecting the electrical connector for corrosion. Mechanics also misdiagnose Mitsubishi vehicles by ignoring the battery, as C1750 on those models indicates a system voltage drop.

Is a pedal relearn required after replacing the sensor?

Yes, most modern vehicles require an electronic pedal relearn procedure after replacing the sensor or disconnecting the battery. This calibrates the computer to the new sensor's exact voltage range. Skipping this step guarantees the code and limp mode will return.

Is the accelerator pedal position sensor the same as the throttle position sensor?

No. The Accelerator Pedal Position (APP) sensor attaches to your gas pedal inside the cabin. The Throttle Position Sensor (TPS) mounts on the throttle body in the engine bay.

Why did my traction control light come on with this code?

Traction control and ABS systems rely on accurate throttle data to manage wheel slip. When the pedal signal fails, the computer disables these safety systems to prevent unpredictable acceleration. The light turns off once the pedal sensor is fixed.

Can a bad ground cause code C1750?

Yes. The APP sensor requires a stable ground connection to output an accurate voltage signal. A corroded chassis ground alters this reference voltage, forcing a perfectly good sensor to report out-of-range data.

Key Takeaways

• Code C1750 forces your vehicle into a 30-50 mph limp mode because the computer receives erratic voltage signals from the gas pedal.
• Before buying a $150 replacement sensor, spend 10 minutes cleaning the electrical connector with contact cleaner and checking for bunched-up floor mats.
• Use an OBD-II scanner with live data to verify the APP1 and APP2 sensor voltages rise smoothly from ~0.5V to ~4.5V as you press the pedal.
• On Mitsubishi models, C1750 specifically points to a system voltage drop, meaning you must test the 12V battery and alternator before touching the gas pedal.