P2299 on 2015-2016 Fiat 500L: Understanding the Brake and Accelerator Pedal Conflict Code

What's Unique About the 2015-2016 Fiat 500L

For Fiat Chrysler Automobiles (FCA) vehicles like the 500L, this code is a well-documented and intentional feature. Fiat has issued multiple Technical Service Bulletins (TSBs) clarifying that P2299 is usually caused by the driver's habits—specifically, driving with two feet. The manufacturer explicitly warns technicians *not* to replace the expensive accelerator pedal assembly for this fault alone, as the code is often a sign of the safety system working as designed rather than a component failure.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Electronic Throttle Control (ETC) warning light may be illuminated
• Vehicle may enter 'limp mode' with reduced engine power and poor acceleration
• Cruise control may be disabled.
• ABS or Traction Control warning lights may be on.
• On automatic transmission models, the gear shifter may be stuck in Park.

Most Likely Causes

1. Driver pressing brake and accelerator pedals simultaneously 🔴 High Probability → Shop Accelerator Pedal Assembly This is a behavioral issue, often called 'two-footed driving,' where a driver rests their left foot on the brake pedal while their right foot is on the accelerator. Fiat TSBs #9003413 and #53034160A directly name this as the primary cause.
   How to confirm: Clear the code and test drive the vehicle, consciously using only the right foot for both the brake and accelerator pedals. If the code does not return, driving habit is the confirmed cause. This is a common topic on forums for FCA vehicles, including Ram trucks.
   Typical fix: Change driving style to use only the right foot for both pedals. No parts are required.
   Est. part cost: $0
2. Obstructed or improperly installed floor mat 🟡 Medium Probability A thick or out-of-place floor mat can bunch up behind the pedals, preventing one from returning to its resting position fully. This can cause a sensor to send a false 'pressed' signal.
   How to confirm: Visually inspect the driver's footwell. Ensure the floor mat is properly secured and not interfering with the travel of either the brake or accelerator pedal. A real-world repair on a 2016 Fiat 500 involved simply adjusting the floor mat which was interfering with the brake pedal. 🎬 Learn how to trim floor mats to prevent pedal interference.
   Typical fix: Reposition or replace the floor mat.
   Est. part cost: $0
3. Faulty Brake Light Switch (Stop Lamp Switch) ⚪ Low Probability → Shop Brake Light Switch While less common than driver habit, the brake light switch can fail or stick in the 'on' position. This tells the computer the brakes are applied even when they aren't, creating a conflict when the gas pedal is pressed. Forum users have reported this failure fixing the issue.
   How to confirm: With the vehicle on, have a helper observe the brake lights while you are not touching the pedal. If the brake lights are stuck on, the switch is likely faulty. Conversely, if the brake lights don't work at all or only work when the pedal is pressed very hard, the switch may also be bad. A scan tool can also monitor the switch's live data to see if it's stuck in the 'on' or 'off' state. A simple bypass test involves disconnecting the switch connector and using a jumper wire to bridge the power and signal terminals; if the brake lights illuminate, the switch is confirmed bad.
   Typical fix: Replace the brake light switch. 🎬 See this walkthrough for replacing the Fiat brake light switch. The switch may require adjustment after installation.
   Est. part cost: $20-$50

Rare But Worth Checking

• Wiring or connector issue in pedal circuits: Corrosion or damage to the wiring or connectors for either the brake or accelerator pedal sensors can cause erratic signals. On the Fiat 500 family, the tailgate wiring harness is a known weak point that can fail and cause various electrical issues, including with the brake lights. A 500L owner on fiatforum.com also reported multiple electrical faults stemming from a broken wire harness in the passenger door.
• PCM software issue: On some older Fiat models (2012-2013 500), a TSB (18-007-14 REV. A) linked P2299 to a crank/no-start condition resolved with a PCM software update. A separate TSB for other FCA vehicles (18-053-16) also lists P2299-00 as a code addressed by a software flash, indicating that the PCM's sensitivity can sometimes be a factor.

Diagnosis Steps

1. Ask the primary driver about their driving habits. Do they drive with two feet? This is the most crucial first step.
2. Clear the fault code using an OBD-II scanner.
3. Perform a test drive, making a conscious effort to use only the right foot for both the accelerator and brake pedals.
4. If the code does not return, the issue is resolved.
5. If the code returns, inspect the driver's side floor mat to ensure it is not obstructing either pedal's movement.
6. Check if the brake lights are stuck on or are not working at all. If either is true, the brake light switch is the most likely hardware culprit.
7. Using a scan tool with live data capability, monitor the signals from the Brake Pedal Position (BPP) sensor and the Accelerator Pedal Position (APP) sensor. Confirm they are reporting accurate positions (e.g., 0% throttle and 'Brake Off' when pedals are not pressed). Verify the BPP sensor isn't 'stuck' in a pressed state in the data.
8. If a sensor signal is erratic or incorrect, inspect its wiring and connector for damage or corrosion before condemning the sensor itself. Pay attention to known problem areas like the main chassis ground strap and door/tailgate wiring harnesses.
9. If the brake light switch is suspect, perform a bypass test by jumping the connector terminals to see if the brake lights illuminate.
10. Only consider replacing a part if live data confirms it is sending incorrect information and the wiring is intact.

Parts You'll Likely Need

• Brake Light Switch (OEM #68073610AA (supersedes 68094764AA)) — In the rare event that a part has failed, a sticking or faulty brake light switch is the most probable hardware cause for this code, after driver habit has been ruled out.
  Trusted brands: Mopar, Bosch, Standard Motor Products
  OEM price range: $25-$40
  Aftermarket price range: $15-$30

Related Codes That Often Appear With This One

• P2299-62 — This is a manufacturer-specific sub-code for P2299, meaning 'Accelerator/brake coherency - Signal compare failure'. It can be seen with advanced scanners like MultiECUScan and confirms the nature of the fault.
• P2122 — According to TSB #9003413, this code for 'Accelerator Pedal Position Sensor 1 Circuit Low' can be set if the accelerator pedal connector is disconnected during diagnosis of P2299.
• P2127 — According to TSB #9003413, this code for 'Accelerator Pedal Position Sensor 2 Circuit Low' can also be set if the accelerator pedal connector is disconnected during diagnosis.
• P1220-62 — Seen in a fiatforum.com post alongside P2299, this code for 'Accelerator pedal potentiometer (feasibility) - Signal compare failure' directly points to a conflict in pedal signals, corroborating the P2299 diagnosis.

Technical Service Bulletins (TSBs) & Recalls

• 9003413: States P2299 is usually caused by a 'two footed driver' and the accelerator pedal should not be replaced.
• 53034160A: Repeats the warning about two-footed drivers and advises checking wiring before replacing the accelerator pedal.
• 18-053-16: Defines P2299-00 as 'Brake Pedal Position/Accelerator Pedal Position Incompatible' as part of a larger list of codes addressed by a PCM software update.

Platform-Specific Known Issues

• TSB Confirmation: Fiat has issued Technical Service Bulletins #9003413 and #53034160A specifically for this code. They state, "DTC P2299 is usually caused by a two footed driver and accelerator pedal should not be replaced for this fault."

Mechanic-Grade Diagnostic Values

• Accelerator Pedal Position Sensor (APPS) Supply Voltage — expected: ~5V. Failure: Voltage significantly lower or higher than 5V indicates a wiring or PCM issue.
• APPS Signal Voltage Redundancy — expected: Signal from potentiometer 2 should be exactly half the voltage of potentiometer 1.. Failure: If the 2:1 ratio is not maintained as the pedal is pressed, the sensor is faulty.
• Brake Light Switch Connector Voltage — expected: ~12V (battery voltage) at the power input pin with ignition on.. Failure: No voltage indicates a fuse or wiring issue upstream of the switch.
• Brake Light Switch Bypass Test — expected: Jumping the power and signal terminals on the connector should illuminate the brake lights.. Failure: If lights turn on with the jumper but not with the switch, the switch is faulty.

Hidden / Shadow Codes Worth Checking

• P2299-62: Accelerator/brake coherency - Signal compare failure. This is a more specific version of the generic P2299 code. (see via Advanced, non-generic scan tools like MultiECUScan.)

Scan Tool Commands That Help

• wiTECH (FCA Dealer Tool): PCM Reprogram/Flash — Used to resolve a P2299 code associated with an intermittent crank/no-start condition on some 2012-2013 Fiat 500s, as per TSB 18-007-14 REV. A.
• wiTECH (FCA Dealer Tool): Cruise Control Learn Procedure — This procedure is required after reprogramming the PCM to ensure cruise control functionality is restored.

Wiring & Ground Locations

• ECU Connector A Pins — At the main IAW 5SF9 Engine Control Unit.. Allows for direct testing of sensor inputs. Pin 14 & 52 are from the brake switch; Pin 51 is from APP sensor 1; Pin 38 is from APP sensor 2.
• Main Engine/Chassis Ground Strap — Runs from the battery negative terminal, to the chassis below the battery tray, and on to the gearbox.. Corrosion or looseness of this primary ground is a known Fiat issue that can cause a wide range of intermittent electrical faults, including erroneous sensor readings that trigger P2299.
• G3022a — Right kick panel.. A ground point in the cabin that could affect BCM or related pedal circuits.
• G31 — Near the Body Control Module (BCM).. The BCM processes the brake switch signal, so a poor ground at this point could affect its interpretation of the signal.

Real Owner Repair Stories

• Carly Blog user 'aaronstern4' (2016 Fiat 500 Diesel) — Brake lights not working and a dash error for the brake light switch.
  ❌ Tried (didn't work) Initial suspicion was a faulty or misaligned brake light switch.
  ✅ What actually fixed it The driver's floor mat had shifted and was interfering with the brake pedal's movement, preventing it from fully returning. Repositioning the floor mat resolved the issue at no cost.

"I Checked Everything" — The Actual Cause

• This code is electrical, so a smoke test is not applicable. However, an analogous situation occurs when all sensors and wiring test perfectly, but the root cause is a physical obstruction. In one documented case for a 2016 Fiat 500, the cause of a brake switch fault was an improperly positioned floor mat interfering with the pedal's travel, which would not be found through electrical testing.

OEM Part Supersession History

• 68094764AA → 68073610AA — Not specified, but typically for improved durability, material change, or minor design revision.
  Heads up: None found. 68073610AA is listed as the direct replacement for the 2014-2020 Fiat 500L.