Rover Has a TSB on this too!
Cut and Pasted Diag proceedure.
Procedure
PROCEDURE
If during diagnosis by TestBook, a P0125 DTC is retrieved:
1. Record the fault on a DTCR.
2. Check the coolant sensor circuit for any signs of loose or poor connections. Repair as necessary and retest.
3. If customer complaints also involve poor heater performance in cold weather, check that the coolant thermostat is installed and functioning property.
If no problem was found in the above check, it will be necessary to update the ECM with PROM set PRM 9631. Before updating, check the tune number by using TestBook. If the tune number is 9631, the update has already been performed and the fault must be with the thermostat, coolant sensor, wiring, or connections.
Follow the instructions to replace the PROM set. This PROM set contains revised diagnostic software which will prevent the fault from reoccurring.
Removal
1. Make sure that the ignition key is turned off.
2. Remove washer reservoir and set aside.
3. Remove ECM cover using suitable tool to remove clips.
NOTE: Ensure that the white anti-backout strips have not fallen out of the connectors. If so, replace them in the connectors.
4. Unplug the ECM connectors. Remove ECM.
5. Place ECM, red connector side up, on grounded antistatic mat. Be sure to wear grounding wrist band.
6. Remove five Torx(R) screws (t2O) from cover, and remove red connector side.
NOTE: Circuit board is easily damaged. Do not pry covers off using screwdrivers or the like.
7. Remove 8 Torx(R) screws holding circuit board.
8. Fold circuit board over onto mat, exposing chips (figure 1).
9. Using suitable pliers, carefully remove blue and green PROM covers (figure 2).
10. Remove the exposed PROM with PROM puller supplied with anti-static mat.
Installation
CAUTION: Make sure that the notch on the PROMs are in line with the notch on the PROM sockets. PROM notch will be oriented towards the red connector.
1. Carefully install new PROMs, noting that one PROM has 28 pins and the other 32 pins.
2. Check for bent pins before replacing PROM covers.
3. Position circuit board and fasten with screws.
4. Install outer cover. Fasten with screws removed earlier. Torque to 2.25-2.82 Nm (20-25 lb. in).
5. Apply the self-adhesive update label on the side of the ECM to signify that the update has been done.
6. Reconnect wire harnesses and install ECM.
7. Install ECM protective cover and washer reservoir.
VERIFICATION AND ROAD TEST
A. Switch on ignition. The fuel pump should rum for a short period. Listen for any unusual noises such as injectors operating or relays clicking which would indicate a problem.
B. Observe that the Check Engine light comes on and stays on during the bulb check. If not, check the multiple connection. If necessary, replace the ECM.
C. If the vehicle fails steps A or B, recheck the multiple connector pins and socket. If this does not resolve the problem, check that the PROM was installed correctly.
8. Perform quality check procedure below.
QUALITY CHECK PROCEDURE
Start engine and observe the following:
1. The "Check Engine" light remains out
2. Idle speed smoothness is stabilized.
3. Switch on A/C, and note idle speed compensation.
4. Rev the engine; no misfire should be noted.
5. Select drive and note idle speed compensation - automatic only (brakes applied).
9. Roadtest the vehicle (drive cycle B per service bulletin W96-007).
