By iCarsoft Official Store Technical Team, Automotive Diagnostics Editors · Updated October 8, 2026 · Technical sources checked
Quick Answer
C0043 concerns a brake-pedal position circuit B family in the cited mapping. Do not assume that B means a second replaceable sensor or that its reading must match channel A. Preserve the full fault and compare the specified position response, mechanical installation and electrical path before selecting a repair.
What Does the C0043 Code Mean?
NHTSA DOT HS 812 575 lists C0043 as Brake Pedal Position Sensor Circuit B with a subfault. This identifies a selected generic fault family, not a universal sensor layout. The full manufacturer description determines which channel is monitored, how its signal is interpreted and what conditions caused the record. The full fault record determines the test branch.
A position signal describes pedal movement or position as interpreted by a controller. A discrete brake switch reports an operating state instead. Neither alone measures hydraulic braking performance. Where multiple position channels exist, their relationship is defined by the manufacturer. Equal numbers, inverse slopes or a fixed offset cannot be assumed from the letters A and B.
Mechanical position and signal interpretation must agree. Record the resting pedal and accessible sensor mounting condition before adjustment. An obstruction, disturbed bracket or incorrect installation can affect the reference presented to the sensor. Check recent work without assuming causation. Do not alter a brake pushrod or bend a mounting part solely to make a displayed percentage look similar to another vehicle.
The NHTSA report supplies the selected label only; it does not establish a C0043-specific vehicle repair, calibration or voltage range. No model-specific C0043 bulletin is claimed in this guide. Obtain the current VIN procedure before interpreting the suffix or testing a circuit. In particular, a published repair for adjacent C0042 is not evidence that the same repair applies to C0043.
A useful diagnostic comparison records the exact channel labels, units, storing module and pedal condition together. If one reading remains fixed while another changes, that observation needs the applicable PID definition and circuit tests before assigning a cause. A missing data item can also reflect tool coverage. Do not convert an incomplete generic scan screen into proof of a dead sensor or failed controller.
Separate C0043 from adjacent fault families
| Code | General description | Key distinction |
|---|---|---|
| C0043 | Pedal-position circuit B | Use the actual channel relationship and complete OEM code. |
| C0042 | Generic pedal-position circuit A | An adjacent code or its service bulletin is not a C0043 repair instruction. |
| C0041 | Brake-pedal switch B | Switch state and position sensing are different observations. |
| C0044 | Brake-pressure sensor A | Pressure feedback requires its own diagnostic procedure. |
Record the complete C0043 description. Use the exact module, suffix and OEM procedure to select the test path.
C0043 Symptoms and Likely Causes
Record C0043 symptoms and fault status; symptoms alone cannot identify a failed part.
Check whether companion faults share a proven cause.
A pedal-position input concern can accompany brake-control or stability warnings depending on the vehicle. Save the exact message and module record. The generic code does not specify which functions remain available.
A supported B-channel value may appear fixed, discontinuous or implausible under the actual complaint. These are observations to test against OEM criteria, not proof of sensor failure or a universal expected waveform.
Lamp, cruise or interlock behavior may help where the actual vehicle uses this signal. Confirm the wiring and function before linking the complaint to C0043. Never defeat an interlock to continue driving.
A disturbed connector, sensor seating issue or mounting error may deserve attention after service. Record what changed and inspect it using the manufacturer sequence. The timing of recurrence alone does not establish a defective part.
Practical cause-checking order
- Pedal reference or mounting: Inspect normal pedal return and the installed sensor relationship. Check accessible interference and disturbed brackets using the approved procedure. Mechanical alignment must be established before changing a learned reference or condemning an electronic part.
- Terminal integrity: Check connector locks, terminal retention and approved contact measurements. A loose connection may produce intermittent behavior when moved, but temporary improvement after touching a connector is not proof of a durable repair.
- Source, return or signal path: Trace the B channel on the correct diagram, including any source or return needed by its design. Follow specified loaded or isolated tests. Do not assume shared supplies, wire count, voltage or pinout from an adjacent code.
- Sensor response: Compare the installed sensor response with the documented test after external paths pass. A repeatable failure attributable to the sensor can support replacement. Do not use an ohmmeter test for a passive device on an electronic assembly unless directed.
- Setup or controller interpretation: Confirm controller configuration and any required setup only in the manufacturer sequence. Check companion communication or supply records where applicable. Do not replace a module because a general-purpose data list omits the requested channel.
Did C0043 appear after recent pedal, position-sensor, connector or interior-trim work? Recheck the documented connections, parts and setup steps affected by that work. Record battery and software history; a post-repair code does not prove the new part is defective.
How Serious Is C0043, and Can You Drive?
Follow the owner manual and actual brake warnings. Stop safely for abnormal braking, fluid loss, dragging or a red brake warning. The code cannot establish safe mileage.
Record brake warnings, pedal changes, fluid loss and recent service. Do not induce wheel slip or emergency braking to test assistance on public roads; warning-state assessment comes before any functional verification.
Stop and arrange a tow if braking changes, pedal effort or travel is abnormal, a wheel drags, fluid leaks or a red brake warning appears.
Follow the exact shutdown and pressure-release procedure before accessing brake components. Support a raised vehicle securely, keep clear of moving parts and never energize unidentified circuits. Do not perform public-road emergency-stop experiments.
How to Diagnose C0043 in the Right Order
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Preserve complete B-channel evidence
Save C0043 with its suffix, storing module, status and available event information before clearing. Record actual warning messages, pedal behavior, functional complaints and recent service. Read relevant companion modules. If braking is abnormal, a red brake warning is present, fluid is leaking or brakes drag, arrange safe recovery instead of driving to reproduce a position signal.
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Map the circuit and expected relationship
Use the current VIN diagram and full-code procedure to locate the monitored B channel. Identify the receiving module, measurement units and required relationship to any other channel. Determine whether the channels share an assembly or circuit resources from actual documentation. Do not infer two sensor housings, identical readings, reversed polarity or a universal released-pedal percentage from the letter B.
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Inspect pedal movement and installation
Secure the vehicle and inspect pedal return, accessible interference, sensor seating and connector retention in the prescribed state. Record the baseline before moving or removing parts. Follow the assembly-specific installation sequence and keep tools clear of pedal mechanisms. Do not adjust brake linkage or bend brackets by trial and error to influence scan data; those actions require their own approved procedure.
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Compare the specified position readings
Observe the required position data during the specified pedal movement. Compare the channel relationship and repeatability with OEM criteria while noting tool sampling and scaling. Correlate actual pedal motion and relevant functional observations. A clean-looking PID does not prove normal brake pressure or stopping ability. If information is unavailable, establish tool coverage before making conclusions about the vehicle.
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Prove the electrical or sensor branch
Follow the manufacturer circuit test in its stated connection and power conditions. Measure the identified source, return and signal path with suitable equipment and proper probes. Isolate connector or wiring defects before condemning the sensor. Do not bridge terminals or apply battery voltage to an unknown input. If external circuits pass, use the specific sensor test before authorizing replacement.
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Verify setup and the original complaint
Correct the proven failure and complete any required initialization or calibration. Repeat the original failed measurement, verify pedal return and relevant vehicle functions, and save the final module scan. Clear only permitted records after evidence is retained. A successful erase does not establish safe braking. If the intermittent event cannot be reproduced under approved conditions, document that remaining uncertainty rather than declaring a guaranteed fix.
Specifications are vehicle-specific. Use the exact VIN specifications, approved test points and required operating state. No generic value or drive cycle can replace the applicable procedure. Manufacturer examples here do not establish specifications for other applications.
C0043 Repairs and Cost Planning
A C0043 repair must address the demonstrated failure. Do not replace an assembly from the code alone.
Recheck installation and required setup after repair. Multiple-channel sensing is not diagnosed by simply demanding equal readings. The correct relationship may be represented differently by the tool, and a displayed value may be scaled rather than a direct terminal voltage. Use documented limits and operating conditions. Save an observation that includes pedal movement and both relevant channels where available; account for scan sampling before calling a brief discrepancy an electrical failure.
Ask the shop to name the failed branch and the measurement supporting each proposed repair.
Authorize diagnosis before parts while the cause remains uncertain.
| Possible path | Quote basis |
|---|---|
| Correct the demonstrated pedal-reference or sensor-installation defect | VIN-specific quote |
| Repair the identified terminal or electrical path | VIN-specific quote |
| Replace the position sensor only after the applicable test fails | VIN-specific quote |
| Perform required setup and verify the original operating condition | VIN-specific quote |
Request an itemized, VIN-specific quote for the proven repair, setup and verification. Check applicable warranty coverage.
Using iCarsoft CR Max P for C0043
On a supported vehicle, iCarsoft CR Max P can save accessible faults, available freeze frame, live data and diagnostic reports. Preserve the C0043 evidence before clearing.
Preserve the brake-pedal position channel B evidence
iCarsoft CR Max P
Review supported codes and relevant live data together. Confirm the exact VIN, controller access, PIDs and any requested active test with iCarsoft before purchase; generic product capabilities do not guarantee a C0043-specific function.
Check current CR Max P price and availabilityCheck CR Max P compatibility by VINConfirm the exact VIN, controller, requested function and software with iCarsoft before purchase. Follow OEM testing prerequisites.
Know the measurement boundary. Scan data describes ECU-provided information; it does not directly prove the physical condition of the brake-pedal position channel B. Use the prescribed independent measurements when required.
Verify the C0043 Repair
After repair, verify connectors, harness clearance, setup and controller supply. Save post-repair findings, then clear only erasable records through the approved procedure. Battery disconnection is not a repair.
Run the manufacturer's applicable verification conditions in a safe workshop or route. Compare the original operating state with current data for the brake-pedal position channel B, and check current and pending faults in related modules. One clean start or idle period does not prove that every conditional monitor has completed.
If C0043 returns, compare its suffix, status, failure order and operating conditions with the saved baseline before replacing another part. Revisit the failed branch and inspect anything disturbed. Confirm the prescribed brake-system verification separately from code clearing.
Stored and Active brake-control faults require different decisions. Preserve the original record and follow the OEM confirmation procedure. A cleared display does not prove restored assistance or safe braking.
Related Brake-Pedal Position Channel B Code Guides
Use each related code's own diagnostic procedure.
C0043 Frequently Asked Questions
Must brake-pedal position channels A and B show the same value?
No universal equality rule is established. The vehicle may scale or interpret channels differently. Compare the actual PIDs and signal relationship with the current OEM procedure, preserving units and module identity. B does not prove a second housing, a particular polarity or a fixed voltage range.
What should I check first for C0043?
Preserve the complete module record and available event data. Confirm the full OEM description, actual architecture and recent work before selecting the required electrical or physical test.
Can I drive with the C0043 code?
Arrange prompt brake diagnosis and follow the owner manual. Do not assume ABS or stability assistance remains available. Abnormal pedal effort, pulling, fluid loss, dragging or a red brake warning requires stopping safely and arranging recovery. The code cannot establish a safe driving distance.
Why did C0043 return after a part was replaced?
Only perform a calibration when the actual C0043 procedure or installation instructions require it. First correct proven mechanical or electrical faults and confirm that the sensor is installed properly. Repeating an unsupported relearn can conceal a baseline without fixing the cause. Verify the failed branch and required functions afterward, and document any intermittent condition that was not reproduced.
What should a C0043 repair estimate include?
Request failed-test evidence and itemized diagnosis, parts, labor, setup and verification costs. The code cannot determine the price.
Can CR Max P diagnose and clear C0043?
On a supported vehicle, CR Max P can organize available faults, freeze frame, live data and reports, and can clear erasable records after repair. Confirm exact ECU coverage. It cannot establish safe braking from an erase command or replace physical measurements for the brake-pedal position channel B.
The iCarsoft Official Store Technical Team maintains the store's fault-code library. This guide organizes published technical references and verified product information; it does not document a hands-on test of a particular vehicle or claim an individual engineer's review.
Technical and cost references
- NHTSA DOT HS 812 575 — Functional Safety Assessment of a Generic Electric Power Steering System. August 2018; Appendix L Table L-2 lists C0043 Brake Pedal Position Sensor Circuit B with a subfault. It does not define a VIN-specific response range or repair.
Product information: Official iCarsoft CR Max P page.
Editorial note: Diagnostic education does not replace the owner manual, current VIN-specific service information or professional inspection. Procedures, coverage and costs vary. Related guides provide context, not interchangeable repair instructions. No universal failure rate, price or outcome is implied.
