Fix P0722: Mechanic’s solutions that WORKED

The code P0722: Output Speed Sensor No Signal points out a fault in the vehicle’s transmission system, specifically indicating an issue with the output speed sensor signal. This sensor is crucial for the transmission control module (TCM) to monitor the transmission’s performance. Common causes include sensor failures, wiring issues, or problems with related components like the ABS module.

P0722 quick overview

Meaning	P0722: Output Speed Sensor No Signal
Is it serious?	This code indicates a significant issue as it affects transmission performance, potentially leading to drivability problems.
Possible causes	– Faulty or damaged output speed sensor – Wiring issues, such as shorts or disconnections – Problems with the transmission control module (TCM) – Malfunctioning ABS controller or module – Incorrect installation of speed sensors, especially post-repair
How to diagnose?	Inspect Speed Sensors: Check the condition and connection of the output speed sensor. Check Sensor Installation: Ensure sensors are correctly installed, particularly after transmission work. Examine Wiring and Connectors: Look for damaged, loose, or corroded wiring, especially near the firewall and A/C lines. Utilize Diagnostic Tools: Use vehicle-specific scanners to accurately read and interpret diagnostic codes. Consider ABS Issues: Investigate potential faults in the ABS controller or module.

How to fix P0722 – learn from mechanics

I looked into P0722 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: Chevrolet

Vehicle Information: 2007 Chevrolet Impala LT 3.5L Transmission

Issue + Repair History:

• Purchased from auction with no forward gears, only reverse.
• OBD2 codes: P0301 (misfire, but engine runs fine), P0722.

Other OBD2 Codes + Test Results:

• P0301: Misfire code.
• P0722: No drive gears.

Suggestions to Fix Issue:

• Check if the low/intermediate band is broken by moving shifter to low gear.
• Unplug the main harness for default action to get transmission to move forward.
• Unplug connector at the transmission to test if there’s any forward movement.
• Consider internal supply line assembly cracking as a cause.
• Remove and replace (R&R) the transmission.
• Check transmission fluid condition and smell.

Final Fix: Broken forward band identified as the issue. Resolved with assistance from community members.

Case #2: Land Rover

Vehicle Information: 2001 Land Rover Discovery Series II LE 4.0L ABS

Issue + Repair History:

• Vehicle presented with ABS, TC, and HDC lights on.
• OBD2 codes found: P0722 and P1590.
• Initially unsure about the cause, suspecting a wheel speed sensor issue.

Other OBD2 Codes + Test Results:

• P0722: Torque converter stall code.
• P1590: Rough road signal.

Suggestions to Fix Issue:

• Check for a broken low/intermediate band or malfunctioning wheel speed sensor.
• Consider using a specific scan tool like Launch x431 or Autologic for accurate diagnosis.
• Suggestion that the issue might be with the left front wheel speed sensor, which requires a hub assembly.
• Clear the codes after repair, as they do not clear automatically.
• Check for torque converter slipping and ABS rough road signal circuit malfunction.
• Use of specific diagnostic tools (Testbook or Autologic) for ABS code retrieval and clearing.

Final Fix: The issue was resolved by replacing the right front wheel speed sensor.

Case #3: Volvo

Vehicle Information: 1999 Volvo V70 X/C AWD 2.4L MIL Lamp on

Issue + Repair History:

• Vehicle setting a P0722 code for vehicle speed sensor.
• Difficulty in pulling code from the vehicle, with no clear diagnostic information available.
• Replacement of the speed sensor eventually fixed the issue.

Other OBD2 Codes + Test Results:

• P0722: Vehicle speed sensor.

Suggestions to Fix Issue:

• A common suggestion was that the ABS controller might be causing the vehicle speed sensor code, due to its high failure rate.
• The possibility that the problem could be with the output speed reference sensor on the transmission.
• The ABS computer was suspected to be the origin of the VSS signal, potentially due to cracked solder joints.
• It was advised that the speed sensor signal originates from the left front ABS sensor and goes to the ABS module first.
• The ABS module was frequently mentioned as a likely cause of the problem.

Final Fix: The issue was resolved by replacing the speed sensor.

Case #4: Hyundai P0722

Vehicle Information: 2002 Hyundai Accent GL 1.6L No Reverse

Issue + Repair History:

• Initially had no reverse, but all forward gears worked normally, without any codes.
• Transmission was rebuilt due to a stripped Sun Shell.
• After rebuilding, the vehicle still had no reverse, and a P0722 code appeared.
• Shifting from drive to reverse enabled reverse gear function.
• Input and output speed sensors were replaced.

Other OBD2 Codes + Test Results:

• P0722: Output speed sensor circuit, no or low signal.
• The issue persisted even after replacing the speed sensors.

Suggestions to Fix Issue:

• Inspect whether shift solenoids are functioning correctly.
• Review electrical connections and TCM (Transmission Control Module) signals.
• Consider the possibility of incorrect installation of input and output speed sensors.
• Check for any relevant Technical Service Bulletins (TSBs) regarding bad TCMs.

Final Fix: Swapping the positions of the speed sensors resolved the issue. The problem was caused by incorrect placement of the sensors as per a diagram from a diagnostic tool, which was labeled incorrectly.

Case #5: Ford

Vehicle Information: 1999 Ford Windstar SE 3.8L MIL Lamp on

Issue + Repair History:

• Intermittent codes: P0720 and P0722.
• The output shaft speed sensor was functioning normally when monitored on scope or scanner.
• The issue did not recur for three months after the initial appearance of the codes.

Other OBD2 Codes + Test Results:

• P0720: Transmission output shaft speed sensor.
• P0722: Transmission output shaft speed sensor wiring.
• Sensor pattern and RPM were normal during testing.

Suggestions to Fix Issue:

• Replace the output shaft speed sensor, which is difficult to access but a common issue.
• Check wiring near the firewall above the A/C lines for signs of rubbing or damage.

Final Fix: Replacing the output shaft speed sensor resolved the issue. Despite the difficulty in accessing the sensor due to its location under the rear exhaust manifold, the replacement fixed the problem. Wiring near the firewall and A/C lines was also inspected but found to be okay.

Advice for P0722	Brief Description of Diagnostic Step
Check/Replace Speed Sensors	Inspect the input and output speed sensors; replace if necessary.
Verify Sensor Installation	Ensure speed sensors are correctly installed, especially after repairs.
Inspect Wiring Near Firewall	Examine wiring for signs of rubbing or damage, particularly near the A/C lines and firewall.
Use Appropriate Diagnostic Tools	Utilize vehicle-specific diagnostic tools for accurate code reading.
Consider ABS Controller/Module Issues	Investigate potential issues with the ABS controller or module.
Monitor Sensor Signals	Use a scope or scanner to monitor the output of speed sensors.