How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission, above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49) and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through the grey wire. The ECU uses this information to regulate fuel and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.
If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing is a bit tricky since there are two connector pins, and they serve different purposes but the most effective way to test it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms if the sensor is in full operation. If you're experiencing issues with this sensor, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss as if the engine was running out of gas or injectors aren't firing any more. Today, i pulled out the spark plugs, three were drenched with gazoline the fourth was dry. I put tissue over each hole in the injector and when i turn the engine on without sparks, the three that have gazoline pop right out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming that the issue is elsewhere.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I'm not sure what to do. I believe that I've ruled everything else out. I'm concerned that i may have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style sensor is the same as the G4 and both are used in the 80, 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or at a parts store. Test them out by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's side). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either more info of these goes wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.
A damaged G28 sensor can cause an inaccurate speed counter for your gearbox, a gearbox that shifts more quickly than normal, and/or a misfire in gear. If you are experiencing any of these problems, it click here is most likely that your sensor is failing and requires replacement. They're cheap and click here easy to find particularly if they're a Bosch model like ours. Alternately, GM's version this part is an option.
5. Tachometer
A failing engine sensor could cause a myriad of issues in your car. It's an essential component of click here the transmission in your Audi because it relays information to the ECU about how fast or slow the car's engine is spinning. This sensor could cause the transmission to fail and other components in the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission check here just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU is then able to process this signal to regulate fuel, timig and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should see the resistance to be around 1000 ohms in these areas. This is a common feature across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du You may also find them in wrecking yards.