error codes 64 and 75

[apollo13]

An elderly relative has a VS V6, one owner since new. It has done only 110000 km and was serviced regularly. The engine light has been coming on, once the temperature guage hits 1/8 to 1/4.
I got the error codes - they are 64 and 75. 64 means left bank too lean. The exhaust sensor does not work until it gets hot, so I can understand the error not appearing on cold starts.
We changed the spark plugs and leads, but that did not help. I presume an exhaust manifold leak would be audible, so then are dirty injectors the most likely cause?

Other problem being 75 which is voltage too low. I expect low voltage could complicate all sorts of things. Curious which error was logged first. I would presume low voltage to trip before the exhaust sensor lean error. Measured battery voltage at rest and with engine running; it looks okay. Car does not have hungry accessories like sound system fitted. Suspect a dodgy connection somewhere, which will be hard to trace. Cleaned the battery terminals and alternator connection, plus reseated all the fuses and relays. Still get the error codes.

 

[ephect]

Change ur o2s, then remove battery terminal to clear codes.

Doubt they've ever been changed, this should sort it out

 

[Bowen]

Have u checked earths? My chasis and engine earths were 16 gauge and corroded caused all sorts of issues!! Replaced with 8 gauge and new / more ground earth points problems disappeared

 

[Bowen]

FYI I also had battery light coming on / off

 

[VS_Pete]

Change ur o2s, then remove battery terminal to clear codes.

Doubt they've ever been changed, this should sort it out

x1 They only good for about 80000k as ephect said buy 2 new ones.

 

[HICOMPVN]

When does an Oxygen Sensor need to be replaced?

Exposure to carbon, soot, harmful gases, anti-freeze, chemicals plus thermal and physical shock will shorten the life of an Oxygen Sensor. This results in increased fuel consumption, poor engine performance and excessive exhaust emissions.

That’s why checking for and replacing a worn out Oxygen Sensor is an important part of every routine service.
Oxygen Sensors with 1 or 2 wires typically have a service life of 50,000kms. While 3 and 4 wire sensors have a service life of approximately 100,000kms.

 

[AA6]

Hey, I had the same codes, engine light coming on etc. By cleaning the o2 sensor connector plugs with electrical contact cleaner I managed to stop the engine light coming on. Its worth trying because I changed both o2 sensors about a year before this started happening.

 

[apollo13]

Have u checked earths? My chasis and engine earths were 16 gauge and corroded caused all sorts of issues!! Replaced with 8 gauge and new / more ground earth points problems disappeared

There is the earth direct from the battery to the body. Another earth to the alternator mounting. My VS has another earth on the firewall (passenger side), the relative's VS does not seem to have this.
Any other earths elsewhere in the car?

 

[apollo13]

Epilogue to original post: I got the cheapest sensors I could find and fitted them. They had no more engine light for 8 days since. Never figured out the low voltage error code. Maybe the sensor shorted out when it got hot?

 

[VS_Pete]

That`s good news.