Fix P0501: Mechanic’s solutions that WORKED

The code P0501: Vehicle Speed Sensor “A” Range/Performance is indicative of a problem in the vehicle speed sensor “A”. This sensor plays a crucial role in providing speed information to the vehicle’s engine control module and transmission control module. A range/performance issue in this sensor can lead to inaccurate speedometer readings, improper shifting patterns in automatic transmissions, and possibly affect the fuel efficiency of the vehicle.

P0501 quick overview

Meaning	P0501: Vehicle Speed Sensor “A” Range/Performance
Is it serious?	This code can be moderately serious as it may affect the vehicle’s speedometer function and could impact transmission shifting and fuel efficiency.
Possible causes	– Faulty or malfunctioning vehicle speed sensor (VSS) – Damaged or corroded wiring and connectors related to the VSS – Issues with the transmission control module (TCM) or engine control module (ECM) – Physical damage to VSS or related components due to accidents or repairs
How to diagnose?	Inspect VSS and Wiring: Thoroughly examine the vehicle speed sensor and its wiring for any signs of damage or corrosion. Check Electrical Connections: Ensure all connectors related to the VSS are secure and free of corrosion. Compare Data Streams: Use diagnostic tools to compare vehicle speed readings between the transmission and engine data streams. Assess Related Components: Examine other related parts like ABS wheel sensors or the instrument cluster for potential issues. Conduct Road Test: Perform a road test with a diagnostic scanner to monitor VSS operation in real-time.

How to fix P0501 – learn from mechanics

I looked into P0501 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Dodge

Vehicle Information: 1999 Dodge Ram 3500 5.9L – Cuts out, No idle above 1800 RPM

Issue + Repair History:

• Customer replaced original 1999 engine with a 2001 5.9 Cummins engine.
• Truck only reaches 1800 RPM in gear but goes up to 3500 RPM out of gear.
• Reprogrammed PCM to 2001 5.9 specifications, but no change observed.
• ABS system configured for different tire size and a Dana rear end.
• Rear speed sensor checked and found to be good.
• Discovered different pin configuration in motor harness for rear speed sensor after engine swap.

Related Repair History:

• ECU reprogrammed to 2001 Cummins 5.9 specifications, but issue persisted.

Computer Codes & Descriptions:

• P0501: Vehicle speed sensor range/performance.
• P0230: Transfer pump circuit out of range.
• P1693: DTC in JTEC module.

Final Fix:

• Issue resolved by addressing the different pin configuration for the rear speed sensor in the motor harness. The incorrect signal was causing the motor to enter “limp mode”.

Case #2: Hyundai

Vehicle Information: 2003 Hyundai Tiburon (Tuscani Elise model) 2.7L – MIL Lamp on

Issue + Repair History:

• No speed signal on scanner, though speedometer works fine.
• No ABS light on.
• Checked all wires, connectors, and terminals, signal present but still throws P0501 code.
• Dealer suggested issue with joint connector C-14, but no such connector on the 2.7L model.
• Replaced VSS and swapped out ECU three times.
• Found out vehicle had the wrong computer installed.

Related Repair History:

• New Vehicle Speed Sensor (VSS) installed.
• ECU swapped out three times.

Computer Codes & Descriptions:

• P0501: VSS circuit range/performance.

Other Test Results:

• Voltage to VSS okay.

Final Fix:

• The problem was due to the wrong ECU being installed initially.
• Vehicle originally had an ECU without ABS for a model with ABS.
• Replaced with the correct ECU (39109-77000) for a model with ABS and 6-speed transmission.
• Once the correct ECU was installed, the speed signal was detected on the scanner.
• The drive cycle was completed, and the vehicle passed the smog test.

Case #3: Volkswagen

Vehicle Information: 1997 Volkswagen Jetta GLS 2.0L – Stall, MIL Lamp on

Issue + Repair History:

• Failed PA emissions with MIL on and codes P0722 and P0304.
• Speedometer works fine, and no problems with shifting.
• Neither code reappeared after clearing and road testing.
• The customer reported vehicle stalling.
• A tune-up was performed, which likely addressed the P0304 (misfire) issue.

Related Repair History:

• Performed a tune-up and cleared the codes.
• Monitored vehicle through driving to complete emissions testing.

Computer Codes & Descriptions:

• P0722: No Output Speed Sensor Signal.
• P0501 – Vehicle speed sensor
• P0304: #4 Cylinder Misfire Detected.

Summary:

• After a tune-up, codes were cleared and did not reappear during the test drive.
• Speedometer readings matched scanner data when diagnosing P0722 (No Output Speed Sensor Signal).
• Customer was informed that the P0722 code might reappear and was advised accordingly.

Case #4: Honda

Vehicle Information: 1996 Honda Civic DX 1.6L – Speedometer Inoperative

Issue + Repair History:

• Speedometer not working, triggering code P0501.
• Speedometer operates when the brake is applied slightly.
• Wiring under the intake manifold checked and appears okay.
• Suspected issue at the harness behind the heater box due to a possible windshield leak, but nothing visible.
• Resolved by addressing a bus bar style connector under the intake manifold.

Related Repair History:

• No prior related repair history.

Other Test Results:

• Vehicle Speed Sensor (VSS) tested and found to be okay.
• Scan test showed P0501.
• PID monitor test showed no reading, but speedometer reads when brake is applied.
• Checked harness under intake, which was okay.

Final Fix:

• Found a bus bar style connector under the intake manifold with 14 wire connections (7 black/yellow, 7 green/black).
• Cut this off and joined the two sets of 7 wires together.
• Although no corrosion was visible, this action resolved the issue.

Case #5: Kia

Vehicle Information: 2004 Kia Rio 1.6L – MIL Lamp on

Issue + Repair History:

• Engine computer scanned, revealing a code for O2 sensor (fixed by replacing B1S1 O2 sensor) and a P0501 code for the vehicle speed sensor.
• Transmission data stream shows normal vehicle speed, but engine data stream always reads zero.
• Conflicting information about the source of the ECM’s vehicle speed signal: either from the speed sensor on top of the transmission or from the right front wheel speed sensor.
• Two wires leading to ECM connector number 2 (pins 12 and 18) were backprobed, showing an AC signal consistent with an ABS sensor signal, yet the data stream still reads 0 MPH.
• Vehicle recently repaired from a severe front crash.

Related Repair History:

• The vehicle was brought in from a body shop after a significant front crash.

Computer Codes & Descriptions:

• P0501: VSS intermittent or no signal.

Final Fix:

• Found several broken wires in the left front fender area, where the vehicle had been repaired after the crash.
• Among the broken wires were those from the right ABS sensor.
• Repairing these wires resolved the issue.

Advice	Description of Diagnostic Step
Check Wiring and Connectors	Inspect the vehicle’s wiring and connectors, particularly around the VSS, for damage, corrosion, or loose connections.
Verify Speed Sensor Function	Test the Vehicle Speed Sensor (VSS) for proper operation, including voltage tests and signal consistency.
Consider Related Components	Look into related components like the ABS wheel speed sensors or the instrument cluster for potential issues.
Examine Impact of Physical Damage	In cases of recent accidents or repairs, inspect for physical damage to wiring or components that might affect the VSS.
Monitor Vehicle Speed in Data Stream	Use a scanner to monitor the vehicle speed in the transmission and engine data streams for discrepancies.