2003 Land Rover Discovery, 80K miles.

Recent Land Rover technician repairs: new brakes (3 Months), new MAS air flow sensor (3 months), new K&N filter (2 months), engine was rebuilt 20K miles ago by qualified Land Rover technician.

OBDII code P1170. Bank A and Bank B too lean.

Light came on 2 weeks ago soon after I changed the oil myself with 6 quarts of 5W30 synthetic and replaced oil filter with OEM filter. At same time, immediately right after I changed the oil, battery was dead. I replaced the battery with high current version and my wife told me the next day, the Check Engine Light came on. It has stayed on ever since. I have tried to reset the light by pressing Tripometer and switching ignition to first position and no results. I have disconnected the battery and waited 5-10 minutes and no luck.

I checked gas cap and it is tight. Could it be the gas? I have been using 87 Octane ever since I bought this car 2 months ago. Also, I have driven the car at full throttle and the light still stays on. Engine runs smooth. No loss of power or fuel efficiency, as far as I can tell.

Any suggestions?

Thanks!

 

1. You'll need a code reader at a minimum to reset the light. From your screen name, I'll assume that you are in the US, so most parts stores will read the codes stored for free. Write down the numbers and post back. Some stores loan the readers, which allows you to reset code. Many stores won't reset codes due to corporate policy. You may have other codes.

2. The RAVE is the factory shop manual. It is a free download below. In it are lots of things, like the fact that 5W30 oil is only accepted by Rover for use to 90F. Page 120 of 1529 in the shop manual.

3. It is not the gas. Plenty of people run regular, but the fuel map is set for premium and you'll get better mpg.

4. Vacuum leak or un-metered air can cause strange codes to pop up.

5. The K/N air filter will allow more dirt to reach your new MAF and shorten the life of it. While they may buy ads on this and other sites, notice that their warranty is void if used off road.

6. 1170 translates to Rover as " Front sensor aged - rear HO2S adaption too lean/too
rich LH bank (NAS and EU-3 only) " - page 331 of the shop manual. In the Bosch ECU manual, it is further described as slow response, indicating O2 sensor is aged. If codes cleared, this one would have to repeat on two drive cycles to bring the light back on. So clearing it may be good for one day.

7. One thing that can read/reset codes is an Ultra Gauge. It can also show real coolant temp, your oem gauge will point at 50% from about 130 - 240F. $69.

8. The oem front drive shaft, if not updated to fully greased, will snap. If this happens at speed, with almost no warning it will try to smash a hole in tranmission case. Rebuild in advance article in our tech area.

9. I liked the rear window of the 69 Charger 500, which was a production run made for NASCAR. Dad owned a dealership. They came in 426 or 440.

 

Thank you for your help!

I disconnected/reconnected the battery and the Check Engine Light turned off. I drove it yesterday for 2-3 miles and the light came back on. I disconnected/reconnected the battery again last night and CEL turned off. I drove it the same 2-3 miles again today light has stayed off.

Would replacing all four O2 sensors, plug wires, and spark plus fix the problem?

Would 5W30 versus 10W40 engine oil make a difference?

Why would all this happen right after a simple oil change, or do you think it's coincidental?

 

Depending on the code, it may have to happen on multiple drive cycles (2 day, or more); so you may not have fixed it yet. Rover specs 30 weight oil up to 90F, that is a different problem and won't throw a code.

 

In the future, pretend you don't have a battery so you don't go messing with it. If you have a code, get it read, repaired and then turned.

 

Thank you for your advice.

Here are the codes:

P1170
P1174

Is this the front passenger O2 sensor or the driver's front O2 sensor?

Thanks!

 

Would plan on replacing both front sensors, if one sensor is "aged" and not responding quickly the other can't be far behind.

 

Thanks Savannah! Will do!

 

You should not be running 87 octane if you want to get all the torque and MPG out of her and not carbon up the engine.
Both front 02's should be changed. What color are your plug wires and when was it last tuned.
Might want to read my major service list posted at the top of this section and do it all, especially the front drive shaft.
Only run a 5/309 oil in the cold of winter, as your manual will tell you, in the hot months you need to stay in the 10/4 to 20/50 range for this engine.

 

Here's my old 68 Charger. Sold it in 2011. Sure miss it. The Little Red Express I still have...


Little Red Express:
http://i1202.photobucket.com/albums/...e272012039.jpg