Fuel Sending Unit??
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 1,023
Likes: 23
From: Metro-East IL
Fuel Sending Unit??
Wife's 2004 C5 has been almost flawless these past 11 years. Up until about 2 months ago. I've tried searching but have been unable to find a thread regarding "fuel sending unit" issues. I know others have had this problem....just not finding it when I search.
Going downhill or when my car is parked even on a slight decline, the gas gage will drive to zero. Once I get her back on level ground or going uphill, the gage slowly comes back. I'm pretty sure its a fuel sending unit problem. The last 3 fill-ups I've put in a bottle of Techtron to see if it will help....nothing so far.
Any other ideas? I really don't want to take her into the dealer....but I may have no choice. I "assume" they have to drop the tank to fix the problem?
Thanks in advance.
Going downhill or when my car is parked even on a slight decline, the gas gage will drive to zero. Once I get her back on level ground or going uphill, the gage slowly comes back. I'm pretty sure its a fuel sending unit problem. The last 3 fill-ups I've put in a bottle of Techtron to see if it will help....nothing so far.
Any other ideas? I really don't want to take her into the dealer....but I may have no choice. I "assume" they have to drop the tank to fix the problem?
Thanks in advance.
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 1,023
Likes: 23
From: Metro-East IL
Pull and post ALL the codes for your car. There are 2 sensors, 1 in each tank. Fuel sensor issues do set DTC's. 
Codes will indicate which tank is experiencing the problem. Post the H or C or HC that follow each 5 character code. Also list the codes under the sensor they appear. ie 10 - PCM or 28- TCS or 40 - BCM etc.
OR
http://www.c5forum.com/ayc/dtcdic.php
Are you adding the large bottle of Techron Plus to a less than half full tank and then filling the tank?? If you use the small bottle you need to add 2 bottles. Several treatments usually clear the problem and then every oil change add another large bottle as preventative care.
If the sensor cannot be cleaned with an additive like Techron Plus then yes you will have to have the tanks dropped for mid year 2003 and newer C5's with the FFS fuel system.
Codes will indicate which tank is experiencing the problem. Post the H or C or HC that follow each 5 character code. Also list the codes under the sensor they appear. ie 10 - PCM or 28- TCS or 40 - BCM etc.OR
http://www.c5forum.com/ayc/dtcdic.php
Are you adding the large bottle of Techron Plus to a less than half full tank and then filling the tank?? If you use the small bottle you need to add 2 bottles. Several treatments usually clear the problem and then every oil change add another large bottle as preventative care.
If the sensor cannot be cleaned with an additive like Techron Plus then yes you will have to have the tanks dropped for mid year 2003 and newer C5's with the FFS fuel system.
Thanks for the help. I have used the large bottles of Techron the past couple fill-ups. And I always waited until I was below 1/4 of a tank before adding the Techron. Should I continue to add a bottle Techron with each fill-up?
I pulled the codes and here is what I have...
10 - PCM: P0462H
60 - IPC: B0516H & U1160H
99 - HVAC: B0361H & B0367H
A0 - LDCM: U1064H
A1 - RDCM: U1064H
Found out P0462H is a Fuel Level Sensor 1 circuit Low Voltage....
Thanks again...
Last edited by WesC7; Jun 9, 2015 at 10:07 PM.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
Drivers side tank fuel sensor. I would try several more fillups with adding the Techron. The sensor is part of the fuel pump on the drivers side and is NOT inexpensive. Add to that the cost to drop the tanks and a replacement is going to be expensive. I personally would try several more fillups and hope that cleans the sensor before spending big bucks for the replacement.
I totally agree with Chuck.
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 1,023
Likes: 23
From: Metro-East IL
Drivers side tank fuel sensor. I would try several more fillups with adding the Techron. The sensor is part of the fuel pump on the drivers side and is NOT inexpensive. Add to that the cost to drop the tanks and a replacement is going to be expensive. I personally would try several more fillups and hope that cleans the sensor before spending big bucks for the replacement.
