How to Replace an Audi a1 Key fob G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu has to know when the crankshaft reached TDC, and the position of the camshaft, so that it can activate the spark and injectors.
If this sensor audi a1 Key fob fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating chain stretch or a jumped link on the upper timing chain. However, the error code won’t appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky since there are two pins for the connector and they serve different purposes but the best method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is operating at its maximum. If you’re having issues with this component, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a significant decrease in power. It was like the engine was running out of gas. Or, my injectors were not firing. I pulled out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. When I start the engine without sparks, I put a piece of tissue on the top of each hole in the injector, the 3 drenched with gazoline pop out, but the 4th stay closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I get 0ohm. I assume that the problem is somewhere else.
I also tried to reset the PID but with no luck. The car can start when the G28 is unplugged and is running fine when it is connected, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.
I’m not sure what to do. I believe that I’ve all other possibilities out. I’m concerned that i may have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector’s edge facing up). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position of the crankshaft to determine timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these, the diagnostic scanner will show the codes that could trigger an engine shutdown.
Some of the signs of a failed G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or a misfire when you’re in gear. It is possible that your sensor is failing and needs to be replaced if you notice any of these symptoms. The good news is that they are very cheap and easily accessible, especially when you’re looking at a Bosch unit like ours. Alternately, GM’s version this part is a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind a slew of issues in your car. It is a crucial part of the audi a4 key replacement‘s transmission since it relays information to the ECU about how the car’s crankshaft is turning. If the sensor fails, it will affect the performance of the transmission as well as the rest of the car’s components.
The G5 engine speed sensor is located at the outside of the transmission, above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to regulate fuel and boost, and also timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these points. This is a common part that is found across the audi tt key programming 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.