Gmc Yukon P1642 Engine Trouble Code
What is Gmc Yukon P1642?
Gmc Yukon P1642 code can indicate a faulty oxygen sensor, which may eventually damage the catalytic converter (repair cost: $2,000–$2,200). Professional diagnosis costs around $200–$210. Oxygen sensors are often straightforward to replace — check your owner's manual for location and instructions. This issue should be addressed promptly to prevent further damage.
P1642 on the Gmc Yukon
On high-mileage Gmc Yukon examples, P1642 is often the first sign of a failing fuel pressure regulator. Residual fuel pressure bleeds off overnight, causing lean-start conditions that the ECU registers as a fault at the next cold start.
Code Information
| Code Type: | OBD-II Powertrain (P) Trouble Code |
| System: | Powertrain |
| Vehicle: | Gmc Yukon |
| Brand: | Gmc |
| Model: | Yukon |
| Code: | P1642 |
P1642 Gmc Yukon Symptoms
Check Engine Light
Illuminated Gmc Yukon dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Gmc Yukon
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Gmc Yukon
Increased Emissions
Failed emissions test due to P1642
P1642 Code Structure
Understanding what each digit means in the P1642 powertrain trouble code:
| P | 1 | 6 | 4 | 2 |
|---|---|---|---|---|
| Powertrain Code | Fuel And Air Metering | Fuel Temperature Sensor B Circuit Range/Performance | Injection Pump Fuel Metering Control 'B' High | Glow Plug/Heater Circuit 'A' Malfunction |
How to Fix Gmc Yukon P1642
Diagnostic Steps:
Regarding P1642, carefully inspect the wire harness near the intake manifold bracket, best accessed from below near the oil filter. Look for chafing, pinching, or damaged insulation.
Repair Solution:
Disconnected, dirty, or fouled spark plugs commonly prevent proper engine operation. Replace spark plugs every season or 25 hours. Verify proper spark plug gap. If plugs are good, check ignition components: spark plug wires, coils, and ignition module.
Technical Notes:
Parts or components should not be replaced based solely on P1642 DTC. Consult your vehicle service manual for proper diagnostic procedures, possible causes, and required testing before replacement.
Gmc Yukon P1642 Repair Cost
MAF sensor replacement on the Gmc Yukon for a P1642 fault runs $220–$380 at a franchised dealer. OEM-equivalent aftermarket sensors are available for $80–$130 and are a reliable option for vehicles outside the factory warranty period.
P1642 Description
P1642 engine trouble code is related to Glow Plug/Heater Circuit 'A' Malfunction.
Main Cause
The primary reason for P1642 OBD-II Engine Trouble Code is: Fuel Temperature Sensor B Circuit Range/Performance.
Common P1642 Misdiagnosis on the Gmc Yukon
When Gmc Yukon presents P1642 with a concurrent coolant temperature DTC, technicians sometimes replace the thermostat rather than the coolant temperature sensor (CTS). The CTS is a $15–$25 component; the thermostat job carries 1–2 hours of additional labour.
DIY Repair Guide: P1642 on Gmc Yukon
The coolant temperature sensor on the Gmc Yukon is a straightforward DIY item (difficulty 2/5). Have a drain tray ready for the small amount of coolant that spills when the sensor is removed. Top up the cooling system afterwards and check for air pockets.
Preventing P1642 on the Gmc Yukon
The Gmc Yukon benefits from an intake manifold decarbonisation at 50,000-mile intervals when direct injection is fitted. Carbon build-up on intake valve stems restricts airflow and creates the lean conditions that trigger P1642.
Frequently Asked Questions — Gmc Yukon P1642
A: Yes. A weak battery causes voltage drop during cranking that confuses the ECU and can store a range of fault codes. Always rule out battery and charging system health before diagnosing sensor-related codes.