Hi, please advice
My 1995 XJR Running very rich — CO on 8%. Full steam ahead… Fault code (DTC) C1495 — Throttle flap -potentiometer electrical or mechanical.

Already done:
1. The fault codes (DTCs) read with factory original test unit, WDS, and only DTC shown is C1495 — Throttle flap -potentiometer electrical or mechanical.
Exhaust manifolds welded before my ownership, seems to be ok still, not blowing and underneath checked with mirror also. May need to double check the gasket surface tho’.
2. Measured the throttle flap -potentiometer with ohm-meter from ECM end connector and seems to be working ok, tho’.
3. Just in case fuel injectors cleaned and tested, ok.
4. Just in case Crankshaft speed sensor (LHE1640AA) replaced.
5. Fuel pressure ok.
6. Coolant temp sensor tested ok and inlet temp sensor tested ok.
Just in case will change next Lambda downstream sensors (LHE1682BA).

Best regards Hannu

 

All O2 sensors the same and equivalent connector ready Bosch # 13789 and a Walker # ( ? )

Probably time and ensure you do not twist sensor pigtail as made of brittle galvanized wire

I had broken wires sticking out of the insulation when I purchased M'Lady Penelope

There is a correct placement on the 2 sensor connectors as the same and can be crossed ( a check before replacing )

The O2 sensors do take a 12 mm crush washer , mine were missing , can be obtained from a cheap 12 mm spark plug , the X300 spark plug is 14 mm

The O2 sensor removal hex is a 17 mm

The aft O2 sensor connectors are prone to corrosion like on mine

The return wire back to the ECU as the very sensitive return signal is protected as a coax sheild and the shields are grounded as the small terminal post ( 2 one on left and right ) on the rear engine firewall )

The ECU case has an external ground strap , heavy wire

" Throttle flap -potentiometer electrical or mechanical "

to mess with that on the SC engine can be a can of worms to get correct , good idle speed ?

Very rich running can come from a leak in the vacuum system , the leak effect / fuel mixture can change to the better / good on throttle up as the " supply " of vacuum is greatly better able to compensate for a leak


These might save you a O2 sensor change ?

There is a fault potential of damaging the exhaust donut sealing flange in bringing up the downpipes up to the manifolds casting , the 4 down pointing studs on the manifolds can hit the sealing flange and distort them , I did it to mine . this effects final O2 sensor reading extra fresh air bias and makes fuel mixture rich

Pics coming

 

According to Jaguar manual, the description of that fault code is for Traction Control Actuator. I would expect an actual Throttle code (if the X300 actually has any?) to be a Pnnnn code not a Cnnnn. Where did you get your description from?

Here's the description from manual. I'd be very confident this has nothing to do with high emissions readings.





O2 Sensors is a good shout. Does your car have 2 or 4 sensors?

My understanding was that only US models had 4 sensors. RoW had 2. If you have 2 sensors then the Front Sensor (Upstream) is the the one that controls fueling and the one you need to be suspicious of.

 

Traction control vertical cylinder actuator can have the 2 wires that go into the bottom of the cylinder missing insulation ( aged brittle insulation ) and shorting ( would expect dash fault light as 1 of the 2 TC dash lights )

 

Hi, Thanks for your very good reply.
Idle is good. MAF is replaced with 2nd hand one, no change.

As you proposed, I will check next lambda sensor shield grounds, crush washers,.. leaks in the inlet manifold side and exhaust manifold flange sealing.
Is it sensible to take the Supercharger away and have a look underneath?
ECM is now loose after wire measurements, need also to check that the ground strap is in place.

Best regards Hannu

 

Hi,
Ref. fault code C….
Thanks for your very good point. You are right, it is for Traction Control Actuator. For some reason, on factory tester, WDS, the description for this fault code is wrong.

and the fault code C1495 is true, my traction control is not working, no warning lights on dashboard. Need to sort out that also.

Best regards Hannu

 

C1495 sounds too familiar as the soldier joint inside the ABS / TC module box with the brake lines from it

I can certainly be wrong , but not a bad fix

 

Hey Parker

No that's C1095