So, after three years finally decided to take the Disco to more appropriate terrain for it (not much one can do with it in FL besides hauling kids to school). Planned a trip to the Georgia mountains and on our way there today the car’s “Check Engine” light turned on. Read the code and it shows P0170.

This happened a few miles after we stopped on the road for gas. Car has 42,000 miles and even with the light on seems to be working fine (normal idle, normal performance and fuel consumption). Question is whether I should:

- Clear the code and see if it comes back
- Just keep driving it until I am back home and can take it to the dealer (I am a bit OCD so the idea of driving around with a dash light on keeps me awake...)
- Take it to the dealer in Atlanta and see if they can take care of it (would lose at least a day of our trip).

Would appreciate feedback from technically abled folks on this forum.

 

You are running outside optimal fuel trim. There is a probably an air leak somewhere in your intake system (MAF, vacuum leak, o2 sensor not seated properly...something like that.)

Your engine isn’t using optimal fuel/air so you will see gas mileage go down a little. That’s really all that should happen. In an older car I wouldn’t worry about it. I’ve let those go for tens of thousands of miles on previous vehicles.

But this being a Land Rover, it could explode tomorrow.

 

Assuming it’s related to the fill up:

bad gas?
not premium?

 

Shell V-Power (93), but I feel it could be gas related. Tank is almost empty so will take it to reserve, refill and then clear the code and see what happens.

 

P0170-

00

Fuel Trim

(Bank 1) - No

sub type

information

Exhaust system leakage

Post catalyst heated oxygen

sensor incorrectly installed

Check exhaust system for

leakage. Rectify as required

NOTE:

Monitor description.

Detects when secondary

fuelling adaptation

control signal is not

plausible

NOTE:

Operational

requirements needed to

allow the monitor to be

fully tested. Drive

vehicle under steady

state conditions for up

to 20 minutes

Pre catalyst heated oxygen

sensor circuit short circuit to

ground, short circuit to power,

open circuit, high resistance

Post catalyst heated oxygen

sensor circuit short circuit to

ground, short circuit to power,

open circuit, high resistance

Pre catalyst heated oxygen

sensor contamination or failure

Post catalyst heated oxygen

sensor contamination or failure

Check post catalyst heated

oxygen sensor is correctly

installed

Refer to the electrical circuit

diagrams and check pre

catalyst heated oxygen sensor

circuit for short circuit to

ground, short circuit to power,

open circuit, high resistance

Inspect connectors for signs of

water ingress, and pins for

damage and/or corrosion

Refer to Electronic Engine

Controls V6 S/C 3.0L - Petrol -

Heated Oxygen Sensors

(HO2S), Diagnosis and

Testing - pinpoint test A

 

Before I bought my D5 I did look into this engine in other older vehicles to get an idea of common problems and the only two I found:

1. Some piece in the supercharger that cracks (for which there is an aftermarket strengthened replacement but JLR dealers just just replace the whole supercharger)
2. The oxygen sensors in the exhaust.

So the refuel could have been coincidence and an o2 sensor may have actually died.

I’m sure there are other issues but those two were the most common re this engine which gave me some comfort in buying it.