3.0 auto gearbox malfunction code P0720

[D5AUL]

So I appear to have the first problem with h my 2006 X Type 3.0 sport premium Auto since I've had it.
I went to use it tonight, pulled away & just didn't feel right, the gear changing was really rough & within a few yards the dash light came on & the display said gearbox malfunction.
I plugged in my OBD sensor with the Dash command app on my phone & received code P0720, output speed sensor circuit.
I cleared the code, tried the car again & the fault & code came straight back!
Does anyone have any idea what could be wrong?

[Jaguar Owners Club]

It means the  Output Speed Sensor Circuit Malfunction is throwing up a fault.

Below is a brief description of the fault:

When the code P0720 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is not seeing a rational speed signal from the Output Sensor or, there is a greater than specified RPM difference between the rotational speed of the Input RPM Sensor and the Transmission Output Speed RPM Sensor. This can occur during shifting or when driving at steady speeds in the same gear. It often implies that the transmission is slipping.

Symptoms

• Check Engine Light will illuminate
• Vehicle will not shift properly
• Decrease in fuel economy
• In unusual cases, there are no adverse conditions noticed by the driver
• In some cases, there may be performance problems, such as dying when coming to a stop after driving on the freeway and/or misfire-like symptoms

Common Problems That Trigger the P0720 Code

• Defective Output Speed Sensor
• Defective Shift Solenoids
• Defective Engine Coolant Temperature Sensor
• Defective Valve Body
• Dirty transmission fluid that restricts the hydraulic passages
• Defective Output Speed Sensor wiring or connector

Common Misdiagnoses

• Engine Misfire problem
• Internal Transmission problem
• Driveline problem

[D5AUL]

Thanks for your reply. Yes the symptoms you explain are what I am experiencing.

I spoke to the place I bought it from today, they are a small Indy Garage who had maintained the car for its previous owner for many years. less than 10k miles ago & about 2 years ago the gearbox was removed, stripped, speed sensors & solenoids replaced then re fitted, I also have the original invoice for this work, the Garage said that as this work had been done, it is extremely unlikely that these components would fail again as improved ones are fitted as replacements.

That would hopefully eliminate 4 of the problems you list.

I can check the Engine Coolant Temperature sensor & see if its connected.

The garage did say a common fault is the wiring that goes from the gearbox to the control unit thats behind the glove box can let water in & makes the connection to the control unit wet often leading to problems, so my first check is to see if any water has come in!

[JOE-DOT-COM]

Hi

does this have the zf 6 speed transmission 6HP26,

cheers

Joe

[D5AUL]

2 hours ago, JOE-DOT-COM said:

Hi

does this have the zf 6 speed transmission 6HP26,

cheers

Joe

No, it is a 5 speed. Was the 6 speed only fitted in the later diesel autos?

[JOE-DOT-COM]

Hi

This is out of the JTIS for that fault code

cheers

Joe

[D5AUL]

Thanks for your replies Joe

I've now got plenty to check at the weekend, as with all things on newer cars, these connectors look really awkward to get to!

[D5AUL]

So today I checked the wiring to the gearbox control module behind the glovebox & found a lot of dirty corroded connections, so a good soaking with WD40 & the car now works perfectly!

Whilst the plugs were out of the module I did a resistance check on the two wires that feed the output speed sensor & got a reading close to the figure in the JTIS details above so am happy that the sensor was good.

Thankyou again for the posts above. I'm now very relieved that the car is now fixed without an expensive gearbox rebuild.