How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located near the edges of the transmission, above the flywheel ring gear. It transmits a signal the ECU via an uncolored wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, just above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors in the right way.
If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain stretching or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test as there are various connector pins, and each one has different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is fully functional, it should read approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if there are problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant drop in power. It was as if the engine had run out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. I put tissue over each injector hole and when i turn the engine on without sparks, the ones with gazoline jump out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. I think the issue is in another location.
I also tried to reset the PID but with no luck. The car can start if the G28 is disconnected and runs fine when it is plugged in, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I'm not certain what to do, i believe that i've eliminated everything else. But i'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or a parts store. It is simple to test them by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black end of the connector). They should be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must know the position and speed of the crankshaft to determine fuel injector timing, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner which could cause engine shut down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or an unfire when in gear. If you are experiencing any of these issues, it is likely that your sensor is going bad and should be replaced. They're inexpensive and easy to locate especially when they're an Bosch unit like ours. You can also choose the GM version of this component is also a good option.
5. Tachometer
A faulty engine speed sensor could be the cause of numerous issues with your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU on how fast or slowly the engine of the car is turning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is situated on the outside of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 through a grey wire. The ECU utilizes this signal to control fuel and boost, and also timig. Visit Homepage relays it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU So, you may find them in wrecking yards.