Service engine soon

[Molon Lave]

Long story short, I usually go to my local mobile station but stopped at this racetrack for the 1st time due to my route. Put about half a tank in, started the car and fuel gauge showed empty and low fuel indicator went on. Turned car off and back on and then showed 3/4 full. Got home turned off, back on and went back to normal. A few days later (today) fuel gauge still normal but service engine soon came on, car seems to be running normal. Too late to go to Auto zone to run codes (if they still do it free). Thoughts or experiences that might help me before I get a chance to run codes?

 

[bigmoose]

I'm guessing EVAP since it happened right after filling up. Codes will tell.

 

[Smooth]

 

[BADBOYSVT]

These cars are getting old . Expect to do some tune up .

 

[BADBOYSVT]

My check engine light been on since my 2 rear o2 sensor need replace .

 

[Molon Lave]

My check engine light been on since my 2 rear o2 sensor need replace .

I’ll be pretty ticked off if it’s O2 sensors. I replaced those about 2 years ago and put on only about 2000 miles.

 

[TK1299]

Have you put the motor under load? I’d say run that tank empty and refill with some good stuff. I got bad fuel in my work car a couple months ago, and after refueling and adding octane boost, I unhooked the battery and reconnected it and everything has been A OK since.

 

[hotcobra03]

You can get codes from instrument cluster

Evap and o2 codes are very common

A o2 code doesn’t always mean bad o2.

Slow to respond I get a lot.

Ok 171/174 is also common

You can reset pcm with removing neg terminal

 

[94 Cobra R]

I’ve had that happen if I filled up my tank and left the car running.


Sent from my iPad using Tapatalk

 

[Molon Lave]

Ok guys, got codes run at Autozone. It’s P0463 fuel level sensor A circuit high input. It’s suggesting fuel pump replacement.

Should I avoid driving the car unnecessarily for fear of running lean?
The write up says a weak pump can cause surging and i wonder if this could be why I’ve been popping FRPS’s?

 

[Wings65288]

Yeah it will definitely cause it to run lean

 

[hotcobra03]

This is fuel gauge.

Has tank ever been removed?

Does car sit a lot?

Float may just be sticking if tank was never removed.

A loose connection also is listed as possible cause

 

[Molon Lave]

This is fuel gauge.

Has tank ever been removed?

Does car sit a lot?

Float may just be sticking if tank was never removed.

A loose connection also is listed as possible cause

This is fuel gauge.

Has tank ever been removed?

Does car sit a lot?

Float may just be sticking if tank was never removed.

A loose connection also is listed as possible cause

Tank was dropped to do some rear end work couple years ago. A week prior to this incident my car was sitting for a week except for backing out of the garage and back in twice. Should I just remember negative from battery and see if service engine pops back on. I’m thinking if it’s something serious it would stay on, if not it would stay off right? Fuel gauge is working fine now. My gauge has wigged out before but never tripped a low fuel indicator or service engine.

 

[bigmoose]

I wouldn't worry about it. I'd clear the code and see if it comes back. That code isn't uncommon if there is a temporary float issue after filling up. If it keeps coming back it could be a connection issue.

 

[BlckBox04]

easiest way to reset everything is disconnect and reconnect the battery. If it's still a problem the light will come right back on an you'll know you have to change some parts.

 

[hotcobra03]

Chilton Library

Scroll down
Here is a backdoor link to full size manual.

Open it. Diagnosis

Onboard.

Charts will show what pintest to follow for code

This link will time out if you pause.

You will need to open from this link each time.

It can be copied.

 

[hotcobra03]

HX76 DTC P0460, P0462 OR P0463: CHECK FUEL TANK LEVEL VOLTAGE RANGE

• Key on, engine running.
  
  
• Access fuel level input voltage (FLI) PID.
  

Is the fuel level input voltage (FLI) PID reading between .25 and 4.5 volts?


Yes No
GO to HX77. GO to HX80.
HX77 CHECK FOR FUEL TANK FLOAT LEVEL RESPONSE

• Key on, engine off.
  
  
• Observe the FLI PID.
  
  
• If fuel level is under one quarter (25% on FLI PID), add fuel (7.57 to 11.36 liters [2 to 3 gallons]) to the fuel tank.
  
  
• If fuel level is greater than three quarters (75% on FLI PID), drain (7.57 to 11.36 liters [2 to 3 gallons]) fuel from the fuel tank.
  

Did the FLI PID indicate a movement upward or downward as fuel is either added or drained?


Yes No
No concern found at this time. GO to Z1 for possible intermittent condition. (Frequent filling of the fuel tank without allowing fuel level to drop below the full mark may contribute to a P0460 DTC.) KEY OFF. REFER to Instrument Cluster Section 413 in the Workshop Manual for inoperative fuel level sender.
HX80 CHECK FLI CIRCUIT VOLTAGE AT FP MODULE

• Disconnect the instrument cluster connector to the fuel gauge. (Refer to Instrument Cluster Section 413 in the Workshop Manual or Wiring Diagram manual for cluster connector configuration.)
  
  
• Key on, engine off.
  
  
• Measure voltage between FLI circuit at the FP module harness connector and battery negative post.
  

Is voltage greater than 5 volts?


Yes No
KEY OFF. GO to HX81. KEY OFF. GO to HX82.
HX81 CHECK FLI CIRCUIT FOR SHORT TO VPWR IN HARNESS

• Disconnect PCM.
  
  
• Key on, engine off.
  
  
• Measure voltage between FLI circuit at the FP module harness connector and battery negative post.
  

Is voltage greater than 10.5 volts?


Yes No
REPAIR short circuit. REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)).
HX82 CHECK FLI CIRCUIT FOR SHORT TO PWR GND IN HARNESS

• Disconnect PCM.
  
  
• Measure resistance between FLI circuit at the PCM harness connector and battery negative post.
  

Is resistance greater than 10,000 ohms?


Yes No
GO to HX83. REPAIR short circuit.
HX83 CHECK FLI CIRCUIT FOR SHORT TO CASE GND IN HARNESS

• Measure resistance between FLI and CASE GND circuits at the PCM harness connector.
  

Is resistance greater than 10,000 ohms?


Yes No
GO to HX85. REPAIR short between FLI and CASE GND circuits.
HX85 CHECK FLI CIRCUIT FOR OPEN IN HARNESS

• Measure resistance of FLI circuit between PCM harness connector and fuel pump (FP) module (pigtail) harness connector.
  
  
• Measure resistance of FLI circuit between PCM harness connector and the instrument cluster fuel gauge harness connector.
  

Is each resistance less than 10.0 ohms?


Yes No
GO to HX86. REPAIR open circuit.
HX86 CHECK CASE GND CIRCUIT FOR OPEN IN HARNESS

• Measure resistance of CASE GND circuit between PCM harness connector and FP module (pigtail) harness connector.
  
  
• Measure resistance between the CASE GND circuit at the PCM harness connector and the fuel gauge ground at the instrument cluster fuel gauge harness connector.
  

Is each resistance less than 10.0 ohms?


Yes No
REFER to Instrument Cluster Section 413 in the Workshop Manual (reference: Wiring Diagram manual) for fuel gauge diagnosis. REPLACE fuel gauge or REPAIR as necessary. Then RERUN Quick Test. If DTC P0460, P0462 or P0463 are still present, REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)). REPAIR open circuit.
HX88 CHECK FUEL CAP LAMP ALWAYS ON W/O DTCS

• Disconnect PCM.
  
  
• Key on, engine off.
  

Is the Check Fuel Cap Indicator Lamp OFF with the PCM disconnected?


Yes No
KEY OFF. REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)). The PCM has not attempted to ground the circuit between the Check Fuel Cap Indicator Lamp and corresponding PCM pin. This has not turned the indicator lamp ON. REFER to Instrument Cluster Section 413 in the Workshop Manual.
HX89 CHECK FUEL CAP LAMP ALWAYS OFF W/O DTCS

• Key off.
  
  
• Disconnect the Check Fuel Cap Indicator Lamp harness connector at the instrument cluster.
  
  
• Disconnect PCM.
  
  
• Measure resistance between PCM harness connector pin (refer to Fuel Cap Off Indicator Lamp PCM Pin Table at the beginning of this pinpoint test for correct pin number) and Check Fuel Cap circuit at the indicator lamp harness connector.
  

Is resistance less than 5.0 ohms?


Yes No
REFER to Instrument Cluster Section 413 in the Workshop Manual to diagnose instrument cluster and Check Fuel Cap Bulb. If OK, REPLACE PCM (REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM)). VERIFY repair by turning key to ON position (lamp will turn OFF in 3 seconds). REPAIR open circuit. VERIFY repair by turning key to ON position (lamp will turn OFF in 3 seconds).

• Intro

 

[hotcobra03]

P0463 - Fuel Level Sensor Circuit High Input The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves above the maximum allowable calibrated parameter for a specified fuel fill percentage in the fuel tank.

• Fuel pump (FP) module concern
  
  
• Incorrectly installed fuel gauge
  
  
• Damaged instrument cluster
  
  
• FLI circuit open
  
  
• FLI shorted to VPWR
  
  
• CASE GND circuit open
  
  
• Overfilled fuel tank
  
  
• Damaged fuel gauge
  
  
• Damaged PCM
  

Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.