A question for any diagnostic trouble code experts out there! P0460
#1
08-22-2013, 03:33 PM
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A question for any diagnostic trouble code experts out there! P0460
I’m trying to diagnose an occasional stall condition that results when I bring my D90 to a stop and idle. It will run fine all day and without reason I’ll have to drive it with one foot on the gas to keep the idle-up so that it doesn’t just quit.
The engine exhibits a malfunction indicator lamp (MIL) so I pulled the DTC codes with an Actron and retrieved 2 error codes:
P0460 (Fuel Level Sensor "A" Circuit - Generic OBD Error Code)
And P3999 (which I believe is not a valid GMS code currently used).
Now I do have a bouncing fuel gauge, (possibly an erratic fuel level sensor/variable resistor in the tank?) but it indicates the correct level when the vehicle is still.
So the question is?? Is the bouncing fuel gauge related - does Rovers’ fuel level sensor talk to the engine because I believed it only signaled the gauge.
-Or- to put it another way - - Is the fuel level sensor (sender) mucking with my ECM (Engine Control Module) or some PCM (powertrain control module)?
Can anyone assist with a similar stall condition and/or a better diagnoses of the code(s).
Thanks
The engine exhibits a malfunction indicator lamp (MIL) so I pulled the DTC codes with an Actron and retrieved 2 error codes:
P0460 (Fuel Level Sensor "A" Circuit - Generic OBD Error Code)
And P3999 (which I believe is not a valid GMS code currently used).
Now I do have a bouncing fuel gauge, (possibly an erratic fuel level sensor/variable resistor in the tank?) but it indicates the correct level when the vehicle is still.
So the question is?? Is the bouncing fuel gauge related - does Rovers’ fuel level sensor talk to the engine because I believed it only signaled the gauge.
-Or- to put it another way - - Is the fuel level sensor (sender) mucking with my ECM (Engine Control Module) or some PCM (powertrain control module)?
Can anyone assist with a similar stall condition and/or a better diagnoses of the code(s).
Thanks
#2
08-22-2013, 03:59 PM
Super Moderator
If the anti-slosh circuit in the dash cluster is not working you'll get rapid meter movement. It is basically a capacitor and resitor to dampen the changes when you round a curve, etc.
Or you could have bad sender in the tank, and there are ECU reasons to monitor low fuel. I would suppose that one could disconnect the fuel sender, and attach a fixed resistor instead, for testing. You would have a steady reading on fuel gauge, and the ECU should be happy with the value not wonking all over the place.
You may also want to clean up the electric connections to the sender and fuel pump under the carpet mat. A fuel pump that stops/starts would not do well to keep you running.
The GEMS manuals has these points, including that test is not done all the time, so may clear and take a few drive cycles to come back.
Two successive trips where the fuel level diagnostic indicates a failed fuel level sensor.
Or you could have bad sender in the tank, and there are ECU reasons to monitor low fuel. I would suppose that one could disconnect the fuel sender, and attach a fixed resistor instead, for testing. You would have a steady reading on fuel gauge, and the ECU should be happy with the value not wonking all over the place.
You may also want to clean up the electric connections to the sender and fuel pump under the carpet mat. A fuel pump that stops/starts would not do well to keep you running.
The GEMS manuals has these points, including that test is not done all the time, so may clear and take a few drive cycles to come back.
3.14 Fuel Level Sensor
3.14.1 Description
1. Diagnostic Trouble Codes:
Fuel level sensor fault: P0460 (P1199 for pre 1997MY vehicles)
Fuel level rationality fault: P0461
2. Monitoring Procedure
Range Check
The resistance of the fuel level sensor changes in relation to the level of fuel in the tank. Through connection to the input resistor networks of the
ECM; any disconnection of the sensor at different points in the harness can generate both high and low input voltages, which are outside the normal
operating voltage range. These are detected to diagnose a fuel level fault in the system.
If the value of FUEL LEVEL VOLTS is less than FUEL LEVEL DIAG MIN VOLTS or more than FUEL LEVEL DIAG MAX VOLTS, then an appropriate
fault counter is incremented up to a limit of FUEL LEVEL DIAGNOSTIC FAULT LIMIT. Otherwise the fault counter is decremented down to a limit of
zero. If the fault counter reaches the limit then a fuel level sensor fault is present.
Rationality Check
The rationality test on the fuel tank level sensor consists of monitoring the fuel level sensor output and ensuring that the output value changes during
a period of time. This test will check that the sensor float is not stuck or holed. The test can be passed either through fuel slosh or a drop in level due
to fuel usage. To ensure that the test can be completed even where the vehicle is being used for successive short journeys, the test parameters are
stored at power down and retrieved at the next power up.
3. Primary Detection Parameter
Fuel level - Measured in volts, the outcome of a potential divider calculation.
4. Fault Criteria Limits
Fuel Level - Low out of range 0.49V
Fuel Level - High 4.8V
Fuel Level change must be less than 2 litres for a period of time greater than 59 minutes
5. Monitoring Conditions
The range test will take place only when the engine is running.
The rationality test will take place when the vehicle speed is greater than 50 mph.
6. Monitoring Time Length / Frequency of Checks
The frequency of the fuel level diagnostic is 2Hz.
7. Criteria for Storing a Diagnostic Trouble Code
3.14.1 Description
1. Diagnostic Trouble Codes:
Fuel level sensor fault: P0460 (P1199 for pre 1997MY vehicles)
Fuel level rationality fault: P0461
2. Monitoring Procedure
Range Check
The resistance of the fuel level sensor changes in relation to the level of fuel in the tank. Through connection to the input resistor networks of the
ECM; any disconnection of the sensor at different points in the harness can generate both high and low input voltages, which are outside the normal
operating voltage range. These are detected to diagnose a fuel level fault in the system.
If the value of FUEL LEVEL VOLTS is less than FUEL LEVEL DIAG MIN VOLTS or more than FUEL LEVEL DIAG MAX VOLTS, then an appropriate
fault counter is incremented up to a limit of FUEL LEVEL DIAGNOSTIC FAULT LIMIT. Otherwise the fault counter is decremented down to a limit of
zero. If the fault counter reaches the limit then a fuel level sensor fault is present.
Rationality Check
The rationality test on the fuel tank level sensor consists of monitoring the fuel level sensor output and ensuring that the output value changes during
a period of time. This test will check that the sensor float is not stuck or holed. The test can be passed either through fuel slosh or a drop in level due
to fuel usage. To ensure that the test can be completed even where the vehicle is being used for successive short journeys, the test parameters are
stored at power down and retrieved at the next power up.
3. Primary Detection Parameter
Fuel level - Measured in volts, the outcome of a potential divider calculation.
4. Fault Criteria Limits
Fuel Level - Low out of range 0.49V
Fuel Level - High 4.8V
Fuel Level change must be less than 2 litres for a period of time greater than 59 minutes
5. Monitoring Conditions
The range test will take place only when the engine is running.
The rationality test will take place when the vehicle speed is greater than 50 mph.
6. Monitoring Time Length / Frequency of Checks
The frequency of the fuel level diagnostic is 2Hz.
7. Criteria for Storing a Diagnostic Trouble Code
Two successive trips where the fuel level diagnostic indicates a failed fuel level sensor.
Last edited by Savannah Buzz; 08-22-2013 at 04:39 PM.
#3
08-23-2013, 05:17 PM
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A wonky D90 Ha!
Savannah Buzz, Thanks for responding.
I had to laugh because “wonking” describes needle action on my fuel gauge very accurately.
So the more pressing question first (so I know if I’m chasing two discreet problems) Do you believe an erratic fuel level signal will signal the ECM to alter engine conditions?
And second would that anti-slosh circuit be a cap and resistor inside the gauge? Because I did substitute a new resister inside the gauge (thinking that could be a gauge issue last year) but to no avail the needle kept bouncing.
I mean, I live with the aggravation of reading my fuel levels before I hit the trail but if it’s “Also” the cause of my stalling then I have to resolve it. And thanks for that GEMS info!
I had to laugh because “wonking” describes needle action on my fuel gauge very accurately.
So the more pressing question first (so I know if I’m chasing two discreet problems) Do you believe an erratic fuel level signal will signal the ECM to alter engine conditions?
And second would that anti-slosh circuit be a cap and resistor inside the gauge? Because I did substitute a new resister inside the gauge (thinking that could be a gauge issue last year) but to no avail the needle kept bouncing.
I mean, I live with the aggravation of reading my fuel levels before I hit the trail but if it’s “Also” the cause of my stalling then I have to resolve it. And thanks for that GEMS info!
#4
08-23-2013, 09:45 PM
Super Moderator
#6
08-26-2013, 09:51 PM
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Alrighty; I am hoping it’s unrelated.
My thought originally developed when I noted the electrical connection between the Fuel Tank to> Gauge –and another- Fuel Tank to> ECM indicated on Instruments wiring schematic (47.2)
AND after just diagnosing a different 95 Ford code last week “[Diagnostic trouble code (DTC) P115A may set with a low fuel level input. If an excessively low fuel level input message is received by the PCM (Power Control module) from the instrument cluster, the PCM limits the injection control pressure (ICP). This may cause a lack of power, rough idle, or other drivability concerns.]”
So, I’ll ohm the wires to determine the first problem is in the tank. Which probably means a new fuel pump if the sender is not a replaceable part or reparable – probably best that I not go soldering new components and such on a sender in a pond of gasoline.
Which leaves the second problem still under the bonnet? Any other thoughts on the stall? I’ve already cleaned the throttle body and Mass Air Flow Sensor just to start.
My thought originally developed when I noted the electrical connection between the Fuel Tank to> Gauge –and another- Fuel Tank to> ECM indicated on Instruments wiring schematic (47.2)
AND after just diagnosing a different 95 Ford code last week “[Diagnostic trouble code (DTC) P115A may set with a low fuel level input. If an excessively low fuel level input message is received by the PCM (Power Control module) from the instrument cluster, the PCM limits the injection control pressure (ICP). This may cause a lack of power, rough idle, or other drivability concerns.]”
So, I’ll ohm the wires to determine the first problem is in the tank. Which probably means a new fuel pump if the sender is not a replaceable part or reparable – probably best that I not go soldering new components and such on a sender in a pond of gasoline.
Which leaves the second problem still under the bonnet? Any other thoughts on the stall? I’ve already cleaned the throttle body and Mass Air Flow Sensor just to start.
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