What is p0300 dtc codes on a 1999 gm pickup? - C1500 GMC Cars & Trucks

P0300 is a random miss fire , a vacuum leak can cause this as well as low fuel pressure ! weak fuel pump , clogged fuel filter !
DTC P0171: Fuel Trim System Lean Bank 1
DTC P0174: Fuel Trim System Lean Bank 2 These two codes are saying the PCM - engine computer is see a lean condition .
DTC P0191: Fuel Rail Pressure (FRP) Sensor Performance
Circuit/System Description
The fuel pressure sensor is located on the fuel line. The fuel pressure sensor monitors the fuel pressure in the fuel line. The fuel pump flow control module (FPCM) monitors the voltage signal from the fuel pressure sensor.

You don't say what make , model an year vehicle ! These are for GM vehicles , yours could mean something else . Except the first three , those are genaric codes , same for all makes ! So can't say what this codes are P2097, and P2099 ! Can't mean this P2097 - Post Catalyst Fuel Trim System Too Rich Bank 1
P2099 - Post Catalyst Fuel Trim System Too Rich Bank 2

DTC P0340 will set if the PCM voltage on cylinder #4 signal wire is not pulled to ground (cam signal pulse) when:
Diagnostic Aids
Important: A cam pulse missing may not affect engine operation.
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An open or high resistance on the #1 plug wire or plug will result in DTC P0340 setting.

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Inspect the EIS towers and plug the wire connections for corrosion or other signs of poor retention at connections.

The electronic ignition (EI) module supplies a signal to the PCM whenever it determines that the #4 cylinder fired on its compression stroke. Because of opposite coil tower polarity, the simultaneous fir of #1 and #4 cylinders are of opposite polarity as well. Under most conditions, except decel, the waste spark cylinder fires before the compression cylinder in sequence. The EI module can determine this polarity sequence and voltage amplitude by using capacitive pickup plates located under the 1/4 coil. If the module senses a positive to negative sequence and high negative spike when #4 is on TDC, it pulls the PCM cam signal to ground signaling that #4 has just fired on compression. This signal along with the double pulse received from the CKP sensor, synchronizes spark and fuel timing.
Beside plugs , plug wires need to be replaced as well !

Well the code is a random miss rather than a specific cylinder.
The noise could be a cam or timing chain problem which would also cause running problems.

A code P0300 may mean that one or more of the following has happened:

• Faulty spark plugs or wires
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector(s)
• Burned exhaust valve
• Faulty catalytic converter(s)
• Stuck/blocked EGR valve / passages
• Faulty camshaft position sensor
• Defective compute
• P1105MAP/BARO Pressure Switch Solenoid Valve
• Check and clean the MAP sensor, or replace.
• P1492EVAP Canister Purge Control/Solenoid Valve (Circuit)
• Replacing the purge solenoid will clear code P1492 This should also clear code P0300 as well.
  

DTC P0300 is a random misfire code, Now you mention evap system yes a evap an cause a random misfire if the system purges at idle this can happen if the purge solenoid get stuck in the open position

DTC P0037; RIGHT-HAND CATALYST MONITOR SENSOR HEATER CONTROL CIRCUIT LOW/HIGH RESISTANCE
DTC P0300; RANDOM MISFIRE DETECTED, MISFIRE DETECTED, PRIMARY CIRCUIT MALFUNCTION
DTC P0305; RANDOM MISFIRE DETECTED, MISFIRE DETECTED,
P1316 IS A MISFIRED OF A CATALYST FOR EX.SPARK PLUG,INJECTOR PRESSURE ,IN GENERAL ITS THE MISFIRED DRIVE CYCLE ...SOMETHING IS FIRING PROPERLY..LET ME ASK HOW MANY MILES DO YOU HAVE.?AND CODE P1111 IS NOTHING TO BE WORRIED ABOUT ITS THE SYSTEM READINESS TEST THAT THE CARS ECM PERFORMS WHEN YOU CUT IT OFF EACH TIME...MAKES SURE THAT ALL IS FUNCTING WELL.

Fuel Sys, Driveability, Filters (Air & Fuel)
2006 CHEVROLET COBALT

02/01/2006 ELIMINATION OF FUEL FILLER TUBE FLAPPER DOOR 03/01/2006 ERRATIC FUEL GAUGE READINGS 06/01/2006 USAGE OF E85 FUELS IN GM VEHICLES - REVISED 06/01/2006 L61 ENGINE MALFUNCTION INDICATOR LAMP (MIL)/SERVICE ENGINE SOON (SES) LAMP ILLUMINATED WITH DTC P0171 "FUEL TRIM SYSTEM LEAN" SET 07/01/2006 TOP TIER DETERGENT GASOLINE - DEPOSITS, FUEL ECONOMY, NO START, POWER, PERFORMANCE, STALL CONCERNS - REVISED 07/01/2006 USE OF E85 FUELS IN VEHICLES NOT CERTIFIED BY GM AS BEING FLEX FUEL COMPATIBLE / AFTERMARKET CONVERSIONS OF VEHICLES TO OPERATE ON E85 FUELS 09/01/2006 397.pdf&btitle=2006 CHEVROLET COBALT&yr=2006">GM FUEL SYSTEM TREATMENT PLUS, FUEL SENDING UNIT CORROSION AND FUEL SYSTEM DEPOSITS - REVISED 11/01/2006 940.pdf&btitle=2006 CHEVROLET COBALT&yr=2006">ERRATIC FUEL GAUGE READINGS - REVISED 03/01/2006 USAGE OF E85 FUELS IN GM VEHICLES - REVISED 12/01/2006 TOP TIER DETERGENT GASOLINE - DEPOSITS, FUEL ECONOMY, NO START, POWER, PERFORMANCE, STALL CONCERNS - REVISED 01/01/2007 EMISSION RECALL - ENGINE FUEL INJECTORS - REPLACE 01/01/2007 LSJ, L61, LK5, L52, LL8 ENGINE - REDUCED ENGINE POWER, MIL/SES LIGHT, DTC P1516, P2135, P2138 02/01/2007 MULTIPLE DRIVEABILITY SYMPTOMS DUE TO CLOGGED FUEL INJECTORS, MIL/SES DTCS P0171, P0172, P0174, P0300, P1174, P1175 - REVISED 03/01/2007 MULTIPLE DRIVEABILITY SYMPTOMS DUE TO CLOGGED FUEL INJECTORS, MIL/SES DTCS P0171, P0172, P0174, P0300, P1174, P1175 - REVISED 05/01/2007 MULTIPLE DRIVEABILITY SYMPTOMS DUE TO CLOGGED FUEL INJECTORS, MIL/SES DTCS P0171, P0172, P0174, P0300, P1174, P1175 - REVISED 06/01/2007 <A href="http://arrc.epnet.com/autoasp/data.asp?sid=122357497&uid=s9193090.remote.autorefctr&type=pdf&ff=082000

P0300 is a multiple cylinder misfire and is used by all OBD2 vehicles on the road in the USA that is 1996 and newer, P0301 is cylinder number 1..P0302 is # 2 and so on...that tune up may have been needed and parts and labor are expensive..you have a cylinder that is misfiring and the cause must be located..possible causes are intake manifold air leaks..secondary ignition problems..fuel injectors..plugged EGR system if it has one..failed head gasket..burned or cracked valves..I have seen some crazy stuff..you need a tech on that one not a mechanic.

Pull out your spark plugs. Change them if dirty. There might be a problem with the fuel trim, thats causing spark plug to foul up prematurely. A stucked open EGR valve can also cause a multiple mispfire code(P0300) but then it would be accompanied by an EGR code(P402) which means excessive flow detected. Anyways if was indeed a fouled up spark plug change them as well as the air filter.

A P0300 DTC is a misfire code. The P1441 is a no flow during purge code which has to do with the purge solenoid. With the misfire code present I would say you have a vacuum leak on one of the hoses. The purge solenoid is located in the passenger side, rear of the intake manifold.