Rick's Free Auto Repair Advice

Ford misfire codes and engine temperature trouble codes

Ford has issued a service bulletin #11-10-5 to address Ford misfire codes and engine temperature trouble codes on the vehicles listed below. The problem stems from a corroded connection at a temperature sensor that makes the PCM think the engine is hotter or colder than it really is. That results in an incorrect air/fuel mixture for the actual engine temperature, causing misfires, incorrect cooling fan operation, lack of power, and stalling.

The check engine light may be on and the following trouble codes stored.

P1285 – Cylinder Head Over Temperature Condition
P1299 – Cylinder Head Over Temperature Protection Active
P0128 – Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

P0301 – Cylinder 1 Misfire Detected
P0302 – Cylinder 2 Misfire Detected
P0303 – Cylinder 3 Misfire Detected
P0304 – Cylinder 4 Misfire Detected
P0305 – Cylinder 5 Misfire Detected P0316
P0316 – Misfire Detected on Startup (First 1000 Revolutions)

Do NOT replace any spark plugs, ignition coils, thermostat or sensors until you perform the diagnostics listed here. The fix may be as simple as replacing a connecter

Ford misfire codes and engine temperature trouble codes on these vehicles:

2010-2012 Fusion, Escape, Transit Connect

2010-2011 Milan, Mariner

2011-2012 MKZ

The TSB 11-8-17 applies to 2010-2012 Transit Connect vehicles with the 2.0L engine, 2010-2012 Fusion, Escape and 2010-2011 Milan, Mariner with a 2.5L or 2.5L Atkinson engine, and 2011-2012 MKZ with a 2.5L Atkinson engine.

The 2.5L Atkinson may exhibit the P1285, P1299, and/or P0128 trouble codes.

Diagnose the problem

Examine the cam cover trough. Remove any debris like leaves, wasps, dirt. Make sure the drain hole at cylinder #4 is open.

Remove the electrical connector at the cylinder heat temperature (CHT) sensor. Check the sensor for evidence of water or corrosion. If you find no sign of water instruction or corrosion, this service bulletin does not apply. Refer to the shop manual for other causes.

If you find water or corrosion, examine the terminals on the electrical connector. If they are rusted or disintegrated, cut off the connector and install a new pigtail


New pigtail

connector #3U2Z-14S411-MDB. Then obtain a new CHT sensor part # 8S4Z-6G004-A.

Cylinder head temperature sensor

Cylinder head temperature sensor


Clean the cam cover with brake parts cleaner. Install the new sensor and apply silicone gasket sealant around the CHT sensor cover to prevent water entry.

Next, check for water entry into the spark plug wells by removing the coil on plug ignition coils. If you find water, dry out the wells, but do NOT remove the spark plugs until the wells are completely dry. Examine the coils for damage and replace where needed.

Ford advises not apply dielectric grease on the boot-to-spark plug well seal—the well must breathe and silicone will prevent that.

©, 2016 Rick Muscoplat

Posted on by Rick Muscoplat

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