How to Replace an audi key replacement cost G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located at the edge of transmission just above the flywheel gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.

If this sensor fails, the ECU will display 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 chain of timing. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging because there are two pins for the connector and they perform different functions but the most effective way to test it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is in full operation. Examine for signs of coolant or oil in the connector bay if there are issues with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power like the engine is out of gas or the injectors are not firing any more. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was unclean. When i crank the engine without sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline jump out but the 4th stays shut. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 i get 0ohm. I'm assuming that the issue is in another location.

I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of -49c even when i unplug it. I also 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 certain what to do, i think i've pretty much completely ruled out all other possibilities. I'm concerned that i may have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in 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 an extra in a wrecking shop or parts store. It is simple to test them: simply switch 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 in our 20vt turbo (3B AAN ABY) engines must know the position and speed of the crankshaft to determine timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go bad you will get codes on the diagnostic scanner which can cause the engine to shut down.

Some of the signs of a failed G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you're in gear. If you experience any of these issues it is likely your sensor is failing and requires replacement. They're cheap and easy to find especially when they're an Bosch model like ours. Alternatively, GM's version of this part is a good option.

5. Tachometer

A failing engine sensor could cause a myriad of issues in your vehicle. It is an important part of the transmission of your audi keys replacement since it sends information to the ECU regarding how fast or slow the engine is spinning. When this sensor fails, it could disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends signals via gray wire to ECU pin T55/49. The ECU then processes this signal to regulate fuel, timig, and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see approximately 1000 ohms of resistance between those points. This is the same across the audi q3 key 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find good ones in wrecking yards.