Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P050B: Cold Start Ignition Timing Control System Performance Problem
- Turn the ignition switch ON (II).
- Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs other than P050B indicated?
YES -Go to the INDICATED DTCS TROUBLESHOOTING .
NO -Go to step 3.
- Check for poor connections or blockage at the air intake duct.
Is it OK?
YES -Go to step 4.
NO -Reconnect or repair the air intake duct, then go to step 25.
- Check for damage at the air cleaner housing.
Is it OK?
YES -Go to step 5.
NO -Replace the air cleaner housing (see AIR CLEANER REMOVAL/INSTALLATION ), then go to step 25.
- Check for dirt or debris in the air cleaner element.
Is it dirty?
YES -Replace the air cleaner element or remove debris (see AIR CLEANER ELEMENT INSPECTION/REPLACEMENT ), then go to step 25.
NO -Go to step 6.
- Let the engine cool until the value of ECT SENSOR 1 is 50°C (122°F) or less.
- Clear the DTC with the HDS.
- Start the engine, and let it idle 10 seconds or more.
- Monitor the OBD STATUS for DTC P050B in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES -Go to step 10.
NO -If the screen indicates PASSED, intermittent failure, the system is OK at this time. If the screen indicates EXECUTING, keep idling until a result comes on. If the screen indicates OUT OF CONDITION, go to step 6.
- Inspect the ignition timing (see
IGNITION TIMING INSPECTION
).
Is the ignition timing OK?
YES -Go to step 12.
NO -Go to step 11.
- Check for damage at the CKP sensor (see CKP SENSOR REPLACEMENT
) and the CKP sensor pulser plate (see
CKP PULSE PLATE REPLACEMENT
).
Is the CKP sensor and/or the CKP sensor pulser plate damaged?
YES -Replace the CKP sensor (see CKP SENSOR REPLACEMENT ) and/or the CKP sensor pulser plate (see CKP PULSE PLATE REPLACEMENT ), then go to step 6.
NO -Go to step 31.
- Do the ETCS TEST in the INSPECTION MENU with the HDS.
Is the THROTTLE ACTUATOR CONTROL VALVE normal?
YES -Go to step 13.
NO -Replace the throttle body; K20Z2 engine (see THROTTLE BODY REMOVAL/INSTALLATION ), K20Z3 engine (see K20Z3 ENGINE ), then go to step 25.
- Start the engine. Hold the engine speed at 3,000 rpm (min-1 ) without load (in Park or neutral) until the radiator fan comes on, then let it idle.
- Monitor the ENGINE SPEED in the DATA LIST with the HDS, and hold the engine speed at 2,500 rpm (min-1 ) for at least 30 seconds.
- While holding the engine speed at 2,500 rpm (min-1
), check the MAF SENSOR in the DATA LIST with the HDS.
Is there about 6-8.6 (K20Z2 engine) or 5.7-8.3 (K20Z3 engine) gm/s?
YES -Go to step 16.
NO -Replace the MAF sensor/IAT sensor (see MAF SENSOR/IAT SENSOR REPLACEMENT ), then go to step 25.
- Turn the ignition switch OFF.
- Drain the coolant (see COOLANT CHECK ).
- Remove ECT sensor 1 (see ECT SENSOR 1 REPLACEMENT ), and ECT sensor 2 (see ECT SENSOR 1 REPLACEMENT ).
- Allow the sensors to cool to ambient temperature.
- Note the ambient temperature.
- Connect ECT sensor 1 to its 2P connector, and ECT sensor 2 to its 2P connector, but do not install them on the engine.
- Turn the ignition switch ON (II).
- Note the value of ECT SENSOR 1 and ECT SENSOR 2 quickly in the DATA LIST with the HDS.
- Compare the value of ECT SENSOR 1 and the ambient temperature, and the value of ECT SENSOR 2 and the ambient temperature individually.
Does either sensor differ more than 3°C (5.4°F) from the ambient temperature?
YES -Replace the sensor that differed more than 3°C (5.4°F) from the ambient temperature, then go to step 25.
NO -Check and repair any problems with the following items, then go to step 25.
- Engine compression and cylinder leakdown
- VTEC system
- Engine oil
- A/C system
- Power steering
- Turn the ignition switch ON (II).
- Reset the ECM/PCM with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Let the engine cool until the value of ECT SENSOR 1 is 50°C (122°F) or less.
- Start the engine, and let it idle 10 seconds or more.
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P050B indicated?
YES -Check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF sensor/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1.
NO -Go to step 31.
- Monitor the OBD STATUS for DTC P050B in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 30, go to the INDICATED DTCS TROUBLESHOOTING .
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF sensor/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1. If the screen indicates EXECUTING, keep idling until a result comes on. If the screen indicates OUT OF CONDITION, go to step 28.
- Update the ECM/PCM if it does not have the latest software (see UPDATING THE ECM/PCM ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Let the engine cool until the value of ECT SENSOR 1 is 50°C (122°F) or less.
- Start the engine, and let it idle 10 seconds or more.
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P050B indicated?
YES -Check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 33. If the ECM/PCM was substituted, go to step 1.
NO -Go to step 36.
- Monitor the OBD STATUS for DTC P050B in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Temporary DTCs or DTCs were indicated in step 35, go to the INDICATED DTCS TROUBLESHOOTING .
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 33. If the ECM/PCM was substituted, go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 33.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.