The first alpha character identifies the system generating the code
The second digit says if the code is generic - same for all OBD-II systems - or manufacturer specific The third digit is sub-system type for that code |
P0300 - Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly. A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.
DIAGNOSTIC: The simplest thing to do is to reset the code and see if it comes back. If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors. Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.
- 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, see tsb issued
- Faulty camshaft position sensor
- Defective computer
- Fuel pressure to high or low
- Cylinder compression low.
- Worn camshaft/broken valve spring(s).
- Fuel injector(s) restricted or leaking.
- Fuel injector(s) continuously open.
- Fuel contamination.
- Fuel injector circuit fault(s). Injector DTCs are also flagged.
- Spark plug failure, fouled or incorrect gap.
- ECM to ignition module primary circuit fault (cylinder misfire DTC is also set).
- Ignition module ground circuit open or high resistance.
- Ignition module or coil failure.
P0727 - Engine speed input signal missing. TCM receives no signal from the ECM. Meaning engine stalls, key still on, ECM still powered up, looking for that signal..... The Engine Control Module (ECM) monitors the engine speed through the Crankshaft Position (CKP) sensor with the engine running, and send signal to the Transmission Control Module (TCM).
DIAGNOSTIC: Check communication error between the ECM and TCM
- Stuck open EGR valve. Probably the most likely candidate.
- Crank Position Sensor. Commonly replaced for these codes, usually never fixes it.
- Pops up if the car runs out of gas, overheats, fuel pump fails, or anything that could cause the engine to stall.
- Open or shorted CKP sensor circuit condition
- Poor CKP sensor electrical connection
- Failed CKP Sensor
P1185 - Upstream lambda heater (oxygen sensor) circuit open, circuit malfunction or EGR Drive Overcurrent (depending on your year car), possible damage from overtightning (27 inch lbs needed)
Test:
1. Ensure that each upstream sensor has a heater resistance of between 5.3 and 6.7 Ohms. If this gives a positive result then go to step 2. If the limits are incorrect then replace the sensor, re-connect the harness and go to step 7.
2. Check harness continuity PI 128/003 to PI 129/003. If this gives a positive result then switch of ignition and go to step 3. If the circuit is open then find the fault and fix it, re-connect the harness and go to step 7.
3. Check harness continuity PI 128/001 to PI 104/030. If this gives a positive result then go to step 4. If the circuit is open then find the fault and fix it, re-connect the harness and go to step 7.
4. Check harness continuity PI 128/004 to RS 006/008. If this gives a positive result then go to step 5. If the circuit is open then find the fault and fix it, re-connect the harness and go to step 7.
5. Check harness continuity PI 129/004 to RS 006/008. If this gives a positive result then go to step 6. If the circuit is open then find the wiring fault and fix it, re-connect the harness and go to step 7.
6. Check harness insulation PI 128/003 to ground. If this gives a positive result then re-connect the harness and go to step 7. If there is a short circuit then find the wiring fault and fix, re-connect the harness and go to step 7.
7. Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 8.
8. Repeat the diagnostic procedure. If this now omits a positive result then stop.
When testing do not test the resistance between sensor pins 3 and 4 as the generated current can damage the platinum electrodes.
P1193 - HO2S heater circuits high resistance both upstream sensors, HO2S heater harness wiring high resistance, HO2S heater harness wiring open circuit, MAFS signal fault, Ignition fault (ignition retard causing high exhaust gas temperature). Both downstream lambda heater (oxygen sensor) circuit open.
- Check connections, verify sensor pulled in proper left and right connectors (not marked).
- Check also conditions in P1185
- Test:
- 1.Ensure that each upstream sensor has a heater resistance between 5.3 and 6.7 Ohms. If this gives a positive result then go to step 2. If the limits are incorrect then replace the sensors, re-connect the harness and go to step 7.
- 2.Check harness continuity PI 126/003 is correctly wired to PI 127/003. If this gives positive results switch off the engine and go to step 3. If the circuit is open then find and repair the fault, re-connect the harness and go to step 7.
- 3.Check harness continuity PI 126/001 is correctly wired to PI 104/004. If this gives a positive result then go to step 4. If the circuit is open then find and repair the fault, re-connect the harness and go to step 7.
- 4.Check harness continuity PI 126/004 is correctly wired to RS 006/008. If this gives a positive result then go to step 5. If the circuit is open then find and repair the fault, re-connect the harness and go to step 7.
- 5.Check harness continuity PI 127/004 is correctly wired to RS 006/008. If this gives a positive result then go to step 6. If the circuit is open then find and repair the wiring fault, re-connect the harness and go to step 7.
- 6.Check harness insulation PI 126/003 will complete a circuit to ground. If this gives a positive result then reconnect the harness and go to step 7. If it short circuits then find and repair the fault, re-connect the harness and go to step 7.
- 7.Clear the fault. Then in order to check if the fault code has been cleared perform the service drive cycle. If this gives a positive result then stop. If the fault is still present then go to step 8.
- Repeat the diagnostic procedure. If this now omits a positive result then stop.
When testing do not test the resistance between sensor pins 3 and 4 as the generated current can damage the platinum electrodes.
P1316 - Misfire Rate Exceeds Emissions, Injector Circuit / IDM Codes Detected
- See P0300 for causes/solutions
P1775 - MIL request from TCM. The P1775 TCM code is set when the engine stalls.
DIAGNOSTIC: Remove the EGR valve (just two bolts and a electrical connector) and see if the pintle valve is stuck and carboned up. It should move freely when pushing it in. If it is hanging up and doesn't close properly this could be the problem.
- Could be the Transmission selector switch, check for flagged TCM DTC's.
- No data exchange between ECM and TCM because of internal fault in the switch
- Crank sensor - remove from car, heat with a blower till hot, check the ohms
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